c++: Fix misuse of "override" in -Weffc++ warnings (PR 94698)

These warnings have nothing to do with virtual functions, so "override"
is inappropriate. The warnings are just talking about defining special
members, so let's say that.

	PR translation/94698
	* class.c (check_field_decls): Change "override" to "define" in
	-Weffc++ diagnostics.

gcc/cp/ChangeLog

+2020-04-22  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR translation/94698
+	* class.c (check_field_decls): Change "override" to "define" in
+	-Weffc++ diagnostics.
+
 2020-04-22 Iain Sandoe <iain@sandoe.co.uk>
 
 	PR c++/94682

gcc/cp/class.c

@@ -3838,13 +3838,13 @@ check_field_decls (tree t, tree *access_decls,
 	  if (! TYPE_HAS_COPY_CTOR (t))
 	    {
 	      warning (OPT_Weffc__,
-		       "  but does not override %<%T(const %T&)%>", t, t);
+		       "  but does not define %<%T(const %T&)%>", t, t);
 	      if (!TYPE_HAS_COPY_ASSIGN (t))
 		warning (OPT_Weffc__, "  or %<operator=(const %T&)%>", t);
 	    }
 	  else if (! TYPE_HAS_COPY_ASSIGN (t))
 	    warning (OPT_Weffc__,
-		     "  but does not override %<operator=(const %T&)%>", t);
+		     "  but does not define %<operator=(const %T&)%>", t);
 	  inform (DECL_SOURCE_LOCATION (pointer_member),
 		  "pointer member %q+D declared here", pointer_member);
 	}