Avoid unnecessary work when -Wmisleading-indentation isn't enabled

gcc/c-family/ChangeLog:
	* c-indentation.c (warn_for_misleading_indentation): Bail out
	immediately if -Wmisleading-indentation isn't enabled.

From-SVN: r224040

gcc/c-family/ChangeLog

+2015-06-02  David Malcolm  <dmalcolm@redhat.com>
+
+	* c-indentation.c (warn_for_misleading_indentation): Bail out
+	immediately if -Wmisleading-indentation isn't enabled.
+
 2015-06-01  Martin Liska  <mliska@suse.cz>
 
 	* c-format.c (check_format_arg):Use new type-based pool allocator.

gcc/c-family/c-indentation.c

@@ -373,6 +373,12 @@ warn_for_misleading_indentation (location_t guard_loc,
 				 enum cpp_ttype next_tok_type,
 				 const char *guard_kind)
 {
+  /* Early reject for the case where -Wmisleading-indentation is disabled,
+     to avoid doing work only to have the warning suppressed inside the
+     diagnostic machinery.  */
+  if (!warn_misleading_indentation)
+    return;
+
   if (should_warn_for_misleading_indentation (guard_loc,
 					      body_loc,
 					      next_stmt_loc,