Add a testcase for r134292.

Part of rdar://9714064

llvm-svn: 134295
diff --git a/clang/test/CodeGen/darwin-thread-specifier.c b/clang/test/CodeGen/darwin-thread-specifier.c
new file mode 100644
index 0000000..605d461
--- /dev/null
+++ b/clang/test/CodeGen/darwin-thread-specifier.c
@@ -0,0 +1,3 @@
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.7.0 -emit-llvm -o - %s | FileCheck %s
+// CHECK: @b = thread_local global i32 5, align 4
+__thread int b = 5;