Unaligned stacks on i686-w64-mingw32 may lead to crashes

Port of original SDL2 patch by Christopher Wellons (@skeeto, #7607)
to SDL3.

src/SDL.c

@@ -632,9 +632,9 @@ SDL_bool SDL_IsTablet(void)
 #ifdef __WIN32__
 
 #if (!defined(HAVE_LIBC) || defined(__WATCOMC__)) && !defined(SDL_STATIC_LIB)
-/* Need to include DllMain() on Watcom C for some reason.. */
+/* FIXME: Still need to include DllMain() on Watcom C ? */
 
-BOOL APIENTRY _DllMainCRTStartup(HANDLE hModule, DWORD ul_reason_for_call, LPVOID lpReserved)
+BOOL APIENTRY MINGW32_FORCEALIGN _DllMainCRTStartup(HANDLE hModule, DWORD ul_reason_for_call, LPVOID lpReserved)
 {
     switch (ul_reason_for_call) {
     case DLL_PROCESS_ATTACH: