patch 8.0.1572: Mac: getting memory size doesn't work everywhere

Problem:    Mac: getting memory size doesn't work everywhere.
Solution:   Use MACOS_X instead of MACOS_X_DARWIN. (Kazunobu Kuriyama)

src/version.c

@@ -766,6 +766,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1572,
 /**/
     1571,
 /**/