Also recognize -std=iso9899:201x

It should already be handled but a typo in the LANGSTANDARD() definition
was introduced in r147220.

Patch by Alexander Richardson, test case by me.

Differential Revision:https://reviews.llvm.org/D27427

llvm-svn: 288793
diff --git a/clang/test/Preprocessor/init.c b/clang/test/Preprocessor/init.c
index d5d83da..b003404 100644
--- a/clang/test/Preprocessor/init.c
+++ b/clang/test/Preprocessor/init.c
@@ -64,6 +64,9 @@
 //
 // 
 // RUN: %clang_cc1 -std=c11 -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix C11 %s
+// RUN: %clang_cc1 -std=c1x -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix C11 %s
+// RUN: %clang_cc1 -std=iso9899:2011 -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix C11 %s
+// RUN: %clang_cc1 -std=iso9899:201x -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix C11 %s
 //
 // C11:#define __STDC_UTF_16__ 1
 // C11:#define __STDC_UTF_32__ 1