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/misc2.pro b/src/proto/misc2.pro
index 644fe2a..7d33de8 100644
--- a/src/proto/misc2.pro
+++ b/src/proto/misc2.pro
@@ -87,7 +87,7 @@
 int same_directory(char_u *f1, char_u *f2);
 int vim_chdirfile(char_u *fname, char *trigger_autocmd);
 int vim_stat(const char *name, stat_T *stp);
-char_u *parse_shape_opt(int what);
+char *parse_shape_opt(int what);
 int get_shape_idx(int mouse);
 void update_mouseshape(int shape_idx);
 void *vim_findfile_init(char_u *path, char_u *filename, char_u *stopdirs, int level, int free_visited, int find_what, void *search_ctx_arg, int tagfile, char_u *rel_fname);