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/if_tcl.c b/src/if_tcl.c
index abef613..eb6684c 100644
--- a/src/if_tcl.c
+++ b/src/if_tcl.c
@@ -1832,11 +1832,11 @@
     while ((next=strchr(text, '\n')))
     {
 	*next++ = '\0';
-	MSG(text);
+	msg(text);
 	text = next;
     }
     if (*text)
-	MSG(text);
+	msg(text);
 }
 
     static void