Removed temporary memory from the API

It was intended to make the API easier to use, but various automatic garbage collection all had flaws, and making the application periodically clean up temporary memory added cognitive load to using the API, and in many cases was it was difficult to restructure threaded code to handle this.

So, we're largely going back to the original system, where the API returns allocated results and you free them.

In addition, to solve the problems we originally wanted temporary memory for:
* Short strings with a finite count, like device names, get stored in a per-thread string pool.
* Events continue to use temporary memory internally, which is cleaned up on the next event processing cycle.

include/SDL3/SDL_events.h

@@ -352,10 +352,6 @@ typedef struct SDL_KeyboardEvent
  * will be inserted into the editing text. The length is the number of UTF-8
  * characters that will be replaced by new typing.
  *
- * The text string is temporary memory which will be freed in
- * SDL_FreeTemporaryMemory() and can be claimed with
- * SDL_ClaimTemporaryMemory().
- *
  * \since This struct is available since SDL 3.0.0.
  */
 typedef struct SDL_TextEditingEvent
@@ -372,10 +368,6 @@ typedef struct SDL_TextEditingEvent
 /**
  * Keyboard IME candidates event structure (event.edit_candidates.*)
  *
- * The candidates are a single allocation of temporary memory which will be
- * freed in SDL_FreeTemporaryMemory() and can be claimed with
- * SDL_ClaimTemporaryMemory().
- *
  * \since This struct is available since SDL 3.0.0.
  */
 typedef struct SDL_TextEditingCandidatesEvent
@@ -393,10 +385,6 @@ typedef struct SDL_TextEditingCandidatesEvent
 /**
  * Keyboard text input event structure (event.text.*)
  *
- * The text string is temporary memory which will be freed in
- * SDL_FreeTemporaryMemory() and can be claimed with
- * SDL_ClaimTemporaryMemory().
- *
  * This event will never be delivered unless text input is enabled by calling
  * SDL_StartTextInput(). Text input is disabled by default!
  *
@@ -792,10 +780,6 @@ typedef struct SDL_PenButtonEvent
  * An event used to drop text or request a file open by the system
  * (event.drop.*)
  *
- * The source and data strings are temporary memory which will be freed in
- * SDL_FreeTemporaryMemory() and can be claimed with
- * SDL_ClaimTemporaryMemory().
- *
  * \since This struct is available since SDL 3.0.0.
  */
 typedef struct SDL_DropEvent
@@ -859,10 +843,6 @@ typedef struct SDL_QuitEvent
  * the programmer; the only requirement is that '''type''' is a value obtained
  * from SDL_RegisterEvents().
  *
- * If the data pointers are temporary memory, they will be automatically
- * transfered to the thread that pulls the event from the queue, or freed if
- * the event is flushed.
- *
  * \since This struct is available since SDL 3.0.0.
  */
 typedef struct SDL_UserEvent
@@ -1420,65 +1400,6 @@ extern SDL_DECLSPEC SDL_bool SDLCALL SDL_EventEnabled(Uint32 type);
  */
 extern SDL_DECLSPEC Uint32 SDLCALL SDL_RegisterEvents(int numevents);
 
-/**
- * Allocate temporary memory.
- *
- * You can use this to allocate memory from the temporary memory pool for the
- * current thread.
- *
- * \param size the amount of memory to allocate.
- * \returns a pointer to the memory allocated or NULL on failure; call
- *          SDL_GetError() for more information.
- *
- * \threadsafety It is safe to call this function from any thread.
- *
- * \since This function is available since SDL 3.0.0.
- *
- * \sa SDL_ClaimTemporaryMemory
- * \sa SDL_FreeTemporaryMemory
- */
-extern SDL_DECLSPEC void * SDLCALL SDL_AllocateTemporaryMemory(size_t size);
-
-/**
- * Claim ownership of temporary memory.
- *
- * This function removes memory from the temporary memory pool for the current
- * thread and gives ownership to the application. The application should use
- * SDL_free() to free it when it is done using it.
- *
- * \param mem a pointer allocated with SDL_AllocateTemporaryMemory().
- * \returns a pointer to the memory now owned by the application, which must
- *          be freed using SDL_free(), or NULL if the memory is not in the
- *          temporary memory pool for the current thread.
- *
- * \threadsafety It is safe to call this function from any thread.
- *
- * \since This function is available since SDL 3.0.0.
- *
- * \sa SDL_AllocateTemporaryMemory
- * \sa SDL_free
- */
-extern SDL_DECLSPEC void * SDLCALL SDL_ClaimTemporaryMemory(const void *mem);
-
-/**
- * Free temporary memory for the current thread.
- *
- * This function frees all temporary memory for the current thread. If you
- * would like to hold onto a specific pointer beyond this call, you should
- * call SDL_ClaimTemporaryMemory() to move it out of the temporary memory
- * pool.
- *
- * This function is automatically called in SDL_Quit() on the main thread and
- * in SDL_CleanupTLS() when other threads complete.
- *
- * \threadsafety It is safe to call this function from any thread.
- *
- * \since This function is available since SDL 3.0.0.
- *
- * \sa SDL_AllocateTemporaryMemory
- * \sa SDL_ClaimTemporaryMemory
- */
-extern SDL_DECLSPEC void SDLCALL SDL_FreeTemporaryMemory(void);
 
 /* Ends C function definitions when using C++ */
 #ifdef __cplusplus