fix PR6287 by accepting and ignoring the returns_twice attribute.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@101005 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Parser/attributes.c b/test/Parser/attributes.c
index ca606f5..b287363 100644
--- a/test/Parser/attributes.c
+++ b/test/Parser/attributes.c
@@ -52,3 +52,7 @@
 void __attribute__((noreturn)) d0(void), __attribute__((noreturn)) d1(void);
 
 void d2(void) __attribute__((noreturn)), d3(void) __attribute__((noreturn));
+
+
+// PR6287
+void __attribute__((returns_twice)) returns_twice_test();