patch 8.0.0663: unexpected error message only when 'verbose' is set

Problem:    Giving an error message only when 'verbose' set is unexpected.
Solution:   Give a warning message instead.
diff --git a/src/message.c b/src/message.c
index a9a6669..aeceee1 100644
--- a/src/message.c
+++ b/src/message.c
@@ -3471,6 +3471,13 @@
     --no_wait_return;
 }
 
+    void
+give_warning2(char_u *message, char_u *a1, int hl)
+{
+    vim_snprintf((char *)IObuff, IOSIZE, (char *)message, a1);
+    give_warning(IObuff, hl);
+}
+
 /*
  * Advance msg cursor to column "col".
  */