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/popupmnu.c b/src/popupmnu.c
index 962a59a..c0191c4 100644
--- a/src/popupmnu.c
+++ b/src/popupmnu.c
@@ -1199,7 +1199,7 @@
     // pum_size being zero.
     if (pum_size <= 0)
     {
-	EMSG(e_menuothermode);
+	emsg(e_menuothermode);
 	return;
     }