patch 9.0.1420: build failure because SIZE_MAX is not defined

Problem:    Build failure because SIZE_MAX is not defined.
Solution:   Define SIZE_MAX when missing. (John Marriott)

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1420,
 /**/
     1419,
 /**/