Update SDL2 to newest version to fix 7.1 playback

This fixes 7.1 playback. Before this commit, SDL used 7.1 front audio configuration with Center Left and Center Right speakers, but without Rear speakers.

See https://github.com/libsdl-org/SDL/issues/11709 for more details.

libs/SDL2/include/SDL_mutex.h

@@ -1,6 +1,6 @@
 /*
   Simple DirectMedia Layer
-  Copyright (C) 1997-2023 Sam Lantinga <slouken@libsdl.org>
+  Copyright (C) 1997-2024 Sam Lantinga <slouken@libsdl.org>
 
   This software is provided 'as-is', without any express or implied
   warranty.  In no event will the authors be held liable for any damages
@@ -23,9 +23,9 @@
 #define SDL_mutex_h_
 
 /**
- *  \file SDL_mutex.h
+ * # CategoryMutex
  *
- *  Functions to provide thread synchronization primitives.
+ * Functions to provide thread synchronization primitives.
  */
 
 #include "SDL_stdinc.h"
@@ -112,13 +112,13 @@ extern "C" {
 #endif
 
 /**
- *  Synchronization functions which can time out return this value
- *  if they time out.
+ * Synchronization functions which can time out return this value if they time
+ * out.
  */
 #define SDL_MUTEX_TIMEDOUT  1
 
 /**
- *  This is the timeout value which corresponds to never time out.
+ * This is the timeout value which corresponds to never time out.
  */
 #define SDL_MUTEX_MAXWAIT   (~(Uint32)0)
 
@@ -165,7 +165,7 @@ extern DECLSPEC SDL_mutex *SDLCALL SDL_CreateMutex(void);
  * unlock it the same number of times before it is actually made available for
  * other threads in the system (this is known as a "recursive mutex").
  *
- * \param mutex the mutex to lock
+ * \param mutex the mutex to lock.
  * \return 0, or -1 on error.
  *
  * \since This function is available since SDL 2.0.0.
@@ -182,7 +182,7 @@ extern DECLSPEC int SDLCALL SDL_LockMutex(SDL_mutex * mutex) SDL_ACQUIRE(mutex);
  * This technique is useful if you need exclusive access to a resource but
  * don't want to wait for it, and will return to it to try again later.
  *
- * \param mutex the mutex to try to lock
+ * \param mutex the mutex to try to lock.
  * \returns 0, `SDL_MUTEX_TIMEDOUT`, or -1 on error; call SDL_GetError() for
  *          more information.
  *
@@ -224,7 +224,7 @@ extern DECLSPEC int SDLCALL SDL_UnlockMutex(SDL_mutex * mutex) SDL_RELEASE(mutex
  * to destroy a locked mutex, and may result in undefined behavior depending
  * on the platform.
  *
- * \param mutex the mutex to destroy
+ * \param mutex the mutex to destroy.
  *
  * \since This function is available since SDL 2.0.0.
  *
@@ -256,7 +256,7 @@ typedef struct SDL_semaphore SDL_sem;
  * is 0. Each post operation will atomically increment the semaphore value and
  * wake waiting threads and allow them to retry the wait operation.
  *
- * \param initial_value the starting value of the semaphore
+ * \param initial_value the starting value of the semaphore.
  * \returns a new semaphore or NULL on failure; call SDL_GetError() for more
  *          information.
  *
@@ -277,7 +277,7 @@ extern DECLSPEC SDL_sem *SDLCALL SDL_CreateSemaphore(Uint32 initial_value);
  * It is not safe to destroy a semaphore if there are threads currently
  * waiting on it.
  *
- * \param sem the semaphore to destroy
+ * \param sem the semaphore to destroy.
  *
  * \since This function is available since SDL 2.0.0.
  *
@@ -301,7 +301,7 @@ extern DECLSPEC void SDLCALL SDL_DestroySemaphore(SDL_sem * sem);
  * This function is the equivalent of calling SDL_SemWaitTimeout() with a time
  * length of `SDL_MUTEX_MAXWAIT`.
  *
- * \param sem the semaphore wait on
+ * \param sem the semaphore wait on.
  * \returns 0 on success or a negative error code on failure; call
  *          SDL_GetError() for more information.
  *
@@ -325,7 +325,7 @@ extern DECLSPEC int SDLCALL SDL_SemWait(SDL_sem * sem);
  * the semaphore doesn't have a positive value, the function immediately
  * returns SDL_MUTEX_TIMEDOUT.
  *
- * \param sem the semaphore to wait on
+ * \param sem the semaphore to wait on.
  * \returns 0 if the wait succeeds, `SDL_MUTEX_TIMEDOUT` if the wait would
  *          block, or a negative error code on failure; call SDL_GetError()
  *          for more information.
@@ -349,8 +349,8 @@ extern DECLSPEC int SDLCALL SDL_SemTryWait(SDL_sem * sem);
  * signal or error, or the specified time has elapsed. If the call is
  * successful it will atomically decrement the semaphore value.
  *
- * \param sem the semaphore to wait on
- * \param timeout the length of the timeout, in milliseconds
+ * \param sem the semaphore to wait on.
+ * \param timeout the length of the timeout, in milliseconds.
  * \returns 0 if the wait succeeds, `SDL_MUTEX_TIMEDOUT` if the wait does not
  *          succeed in the allotted time, or a negative error code on failure;
  *          call SDL_GetError() for more information.
@@ -369,7 +369,7 @@ extern DECLSPEC int SDLCALL SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout);
 /**
  * Atomically increment a semaphore's value and wake waiting threads.
  *
- * \param sem the semaphore to increment
+ * \param sem the semaphore to increment.
  * \returns 0 on success or a negative error code on failure; call
  *          SDL_GetError() for more information.
  *
@@ -387,7 +387,7 @@ extern DECLSPEC int SDLCALL SDL_SemPost(SDL_sem * sem);
 /**
  * Get the current value of a semaphore.
  *
- * \param sem the semaphore to query
+ * \param sem the semaphore to query.
  * \returns the current value of the semaphore.
  *
  * \since This function is available since SDL 2.0.0.
@@ -427,7 +427,7 @@ extern DECLSPEC SDL_cond *SDLCALL SDL_CreateCond(void);
 /**
  * Destroy a condition variable.
  *
- * \param cond the condition variable to destroy
+ * \param cond the condition variable to destroy.
  *
  * \since This function is available since SDL 2.0.0.
  *
@@ -442,7 +442,7 @@ extern DECLSPEC void SDLCALL SDL_DestroyCond(SDL_cond * cond);
 /**
  * Restart one of the threads that are waiting on the condition variable.
  *
- * \param cond the condition variable to signal
+ * \param cond the condition variable to signal.
  * \returns 0 on success or a negative error code on failure; call
  *          SDL_GetError() for more information.
  *
@@ -459,7 +459,7 @@ extern DECLSPEC int SDLCALL SDL_CondSignal(SDL_cond * cond);
 /**
  * Restart all threads that are waiting on the condition variable.
  *
- * \param cond the condition variable to signal
+ * \param cond the condition variable to signal.
  * \returns 0 on success or a negative error code on failure; call
  *          SDL_GetError() for more information.
  *
@@ -486,8 +486,8 @@ extern DECLSPEC int SDLCALL SDL_CondBroadcast(SDL_cond * cond);
  * This function is the equivalent of calling SDL_CondWaitTimeout() with a
  * time length of `SDL_MUTEX_MAXWAIT`.
  *
- * \param cond the condition variable to wait on
- * \param mutex the mutex used to coordinate thread access
+ * \param cond the condition variable to wait on.
+ * \param mutex the mutex used to coordinate thread access.
  * \returns 0 when it is signaled or a negative error code on failure; call
  *          SDL_GetError() for more information.
  *
@@ -512,10 +512,10 @@ extern DECLSPEC int SDLCALL SDL_CondWait(SDL_cond * cond, SDL_mutex * mutex);
  *
  * The mutex must be locked before calling this function.
  *
- * \param cond the condition variable to wait on
- * \param mutex the mutex used to coordinate thread access
+ * \param cond the condition variable to wait on.
+ * \param mutex the mutex used to coordinate thread access.
  * \param ms the maximum time to wait, in milliseconds, or `SDL_MUTEX_MAXWAIT`
- *           to wait indefinitely
+ *           to wait indefinitely.
  * \returns 0 if the condition variable is signaled, `SDL_MUTEX_TIMEDOUT` if
  *          the condition is not signaled in the allotted time, or a negative
  *          error code on failure; call SDL_GetError() for more information.