If strchr can't be folded in gimple-fold...

If strchr can't be folded in gimple-fold, we still need to fall into
the generic code so the folding code in builtins.c is also called.

    gcc/
	* gimple-fold.c (gimple_fold_builtin): After failing to fold
	strchr, also try the generic folding.

From-SVN: r240585

gcc/ChangeLog

+2016-09-28  Wilco Dijkstra  <wdijkstr@arm.com>
+
+	* gimple-fold.c (gimple_fold_builtin): After failing to fold
+	strchr, also try the generic folding.
+
 2016-09-28  Martin Sebor  <msebor@redhat.com>
 
 	PR c/77762

gcc/gimple-fold.c

@@ -2948,7 +2948,10 @@ gimple_fold_builtin (gimple_stmt_iterator *gsi)
     case BUILT_IN_STRNCAT:
       return gimple_fold_builtin_strncat (gsi);
     case BUILT_IN_STRCHR:
-      return gimple_fold_builtin_strchr (gsi);
+      if (gimple_fold_builtin_strchr (gsi))
+	return true;
+      /* Perform additional folding in builtin.c.  */
+      break;
     case BUILT_IN_FPUTS:
       return gimple_fold_builtin_fputs (gsi, gimple_call_arg (stmt, 0),
 					gimple_call_arg (stmt, 1), false);