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/GraphicsUtil.cpp

@@ -4,6 +4,7 @@
 #include <stddef.h>
 #include <stdlib.h>
 
+#include "Alloc.h"
 #include "Graphics.h"
 #include "Maths.h"
 
@@ -226,7 +227,7 @@ void BlitSurfaceColoured(
     }
 
     SDL_BlitSurface(tempsurface, _srcRect, _dest, tempRect);
-    SDL_FreeSurface(tempsurface);
+    VVV_freefunc(SDL_FreeSurface, tempsurface);
 }
 
 void BlitSurfaceTinted(
@@ -287,7 +288,7 @@ void BlitSurfaceTinted(
     }
 
     SDL_BlitSurface(tempsurface, _srcRect, _dest, tempRect);
-    SDL_FreeSurface(tempsurface);
+    VVV_freefunc(SDL_FreeSurface, tempsurface);
 }
 
 
@@ -489,7 +490,7 @@ void ScrollSurface( SDL_Surface* _src, int _pX, int _pY )
     //Cleanup temp surface
     if (part1)
     {
-        SDL_FreeSurface(part1);
+        VVV_freefunc(SDL_FreeSurface, part1);
     }
 
 }