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/ex_getln.pro b/src/proto/ex_getln.pro
index a2d7a9f..298c630 100644
--- a/src/proto/ex_getln.pro
+++ b/src/proto/ex_getln.pro
@@ -4,7 +4,7 @@
char_u *getcmdline_prompt(int firstc, char_u *prompt, int attr, int xp_context, char_u *xp_arg);
int text_locked(void);
void text_locked_msg(void);
-char_u *get_text_locked_msg(void);
+char *get_text_locked_msg(void);
int curbuf_locked(void);
int allbuf_locked(void);
char_u *getexline(int c, void *cookie, int indent);