patch 8.1.0743: giving error messages is not flexible
Problem: Giving error messages is not flexible.
Solution: Add semsg(). Change argument from "char_u *" to "char *", also
for msg() and get rid of most MSG macros. (Ozaki Kiichi, closes
#3302) Also make emsg() accept a "char *" argument. Get rid of
an enormous number of type casts.
diff --git a/src/proto/mbyte.pro b/src/proto/mbyte.pro
index 2ba9f1c..5b97d55 100644
--- a/src/proto/mbyte.pro
+++ b/src/proto/mbyte.pro
@@ -1,6 +1,6 @@
/* mbyte.c */
int enc_canon_props(char_u *name);
-char_u *mb_init(void);
+char *mb_init(void);
int bomb_size(void);
void remove_bom(char_u *s);
int mb_get_class(char_u *p);