updated for version 7.3.535

Problem:    Many #ifdefs for MB_MAXBYTES.
Solution:   Also define MB_MAXBYTES without the +multi_byte feature.  Fix
            places where the buffer didn't include space for a NUL byte.

src/misc1.c

@@ -1932,7 +1932,7 @@ ins_char(c)
     int		c;
 {
 #if defined(FEAT_MBYTE) || defined(PROTO)
-    char_u	buf[MB_MAXBYTES];
+    char_u	buf[MB_MAXBYTES + 1];
     int		n;
 
     n = (*mb_char2bytes)(c, buf);