Replace all free calls with VVV_free[func]

This replaces all calls to SDL_free with a new macro, VVV_free, that
nulls the pointer afterwards. This mitigates any use-after-frees and
also completely eliminates double-frees. The same is done for any
function to free specific objects such as SDL_FreeSurface, with the
VVV_freefunc macro.

No exceptions for any of these calls, even if the pointer is discarded
or zeroed afterwards anyway. Better safe than sorry.

This is a macro rather than a function that takes in a
pointer-to-pointer because such a function would have type issues that
require casting and that's just not safe.

Even though SDL_free and other SDL functions already check for NULL, the
macro has a NULL check for other functions that don't. For example,
FAudioVoice_DestroyVoice does not check for NULL.

FILESYSTEM_freeMemory has been axed in favor of VVV_free because it
functionally does the same thing except for `unsigned char*` only.

desktop_version/src/KeyPoll.cpp

@@ -4,6 +4,7 @@
 #include <string.h>
 #include <utf8/unchecked.h>
 
+#include "Alloc.h"
 #include "Exit.h"
 #include "Game.h"
 #include "GlitchrunnerMode.h"
@@ -183,7 +184,7 @@ void KeyPoll::Poll(void)
                     if (text != NULL)
                     {
                         keybuffer += text;
-                        SDL_free(text);
+                        VVV_free(text);
                     }
                 }
             }