Narrowed criteria for non-standard inclusion.

src/fullscreen.c

@@ -32,7 +32,7 @@
 #include "internal.h"
 
 #include <stdlib.h>
-#if _WIN32
+#if defined(_MSC_VER)
  #include <malloc.h>
 #endif
 

src/window.c

@@ -33,7 +33,7 @@
 
 #include <string.h>
 #include <stdlib.h>
-#if _WIN32
+#if defined(_MSC_VER)
  #include <malloc.h>
 #endif