Always use SDL_malloc() and SDL_free()

To avoid mixing SDL_malloc()/SDL_strdup() with free(), or malloc() with
SDL_free(), always use the SDL version.

app/src/sys/win/command.c

@@ -44,7 +44,7 @@ cmd_execute(const char *path, const char *const argv[], HANDLE *handle) {
 #endif
     if (!CreateProcessW(NULL, wide, NULL, NULL, FALSE, flags, NULL, NULL, &si,
                         &pi)) {
-        free(wide);
+        SDL_free(wide);
         *handle = NULL;
         if (GetLastError() == ERROR_FILE_NOT_FOUND) {
             return PROCESS_ERROR_MISSING_BINARY;
@@ -52,7 +52,7 @@ cmd_execute(const char *path, const char *const argv[], HANDLE *handle) {
         return PROCESS_ERROR_GENERIC;
     }
 
-    free(wide);
+    SDL_free(wide);
     *handle = pi.hProcess;
     return PROCESS_SUCCESS;
 }