objc-runtime-shared-support.c (build_module_descriptor): Set TREE_USED on UOBJC_MODULES_decl.

	* objc-runtime-shared-support.c (build_module_descriptor): Set
	TREE_USED on UOBJC_MODULES_decl.

From-SVN: r224213

gcc/objc/ChangeLog

+2015-06-08  Aldy Hernandez  <aldyh@redhat.com>
+
+	* objc-runtime-shared-support.c (build_module_descriptor): Set
+	TREE_USED on UOBJC_MODULES_decl.
+
 2015-06-05  Aldy Hernandez  <aldyh@redhat.com>
 
 	* objc-act.c (objc_write_global_declarations): Adjust comment.

gcc/objc/objc-runtime-shared-support.c

@@ -519,6 +519,9 @@ build_module_descriptor (long vers, tree attr)
      is referenced by the runtime and, therefore, needed.  */
   DECL_PRESERVE_P (UOBJC_MODULES_decl) = 1;
 
+  /* Squash `defined but not used' warning.  */
+  TREE_USED (UOBJC_MODULES_decl) = 1;
+
   /* Allow the runtime to mark meta-data such that it can be assigned to target
      specific sections by the back-end.  */
   if (attr)