patch 8.1.0779: argument for message functions is inconsistent

Problem:    Argument for message functions is inconsistent.
Solution:   Make first argument to msg() "char *".
diff --git a/src/globals.h b/src/globals.h
index 645c936..d9cd467 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -989,7 +989,7 @@
 					   size is IOSIZE */
 EXTERN char_u	*NameBuff;		/* file names are expanded in this
 					 * buffer, size is MAXPATHL */
-EXTERN char_u	msg_buf[MSG_BUF_LEN];	/* small buffer for messages */
+EXTERN char	msg_buf[MSG_BUF_LEN];	/* small buffer for messages */
 
 /* When non-zero, postpone redrawing. */
 EXTERN int	RedrawingDisabled INIT(= 0);