c++: Change -Weffc++ diagnostic to use "declare" (PR 94698)

Change the wording again, for the reasons given by Jason in
https://gcc.gnu.org/pipermail/gcc-patches/2020-April/544362.html

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

gcc/cp/ChangeLog

+2020-04-22  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR translation/94698
+	* class.c (check_field_decls): Change "define" to "declare" in
+	-Weffc++ diagnostics.
+
 2020-04-22  Patrick Palka  <ppalka@redhat.com>
 
 	PR c++/94719

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 define %<%T(const %T&)%>", t, t);
+		       "  but does not declare %<%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 define %<operator=(const %T&)%>", t);
+		     "  but does not declare %<operator=(const %T&)%>", t);
 	  inform (DECL_SOURCE_LOCATION (pointer_member),
 		  "pointer member %q+D declared here", pointer_member);
 	}