finish COMPATIBLE_SAVES and FIX_INCOMPATIBLE_SAVES

src/skel/crossplatform.h

@@ -33,6 +33,7 @@ char *_strdate(char *buf);
 #endif
 extern DWORD _dwOperatingSystemVersion;
 #define fcaseopen fopen
+#define caserename rename
 #else
 char *strupr(char *str);
 char *strlwr(char *str);
@@ -55,6 +56,8 @@ extern long _dwOperatingSystemVersion;
 char *casepath(char const *path, bool checkPathFirst = true);
 FILE *_fcaseopen(char const *filename, char const *mode);
 #define fcaseopen _fcaseopen
+int _caserename(const char *old_filename, const char *new_filename);
+#define caserename _caserename
 #endif
 
 #ifdef RW_GL3