Implement extern block var.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@47223 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/extern-block-var.c b/test/CodeGen/extern-block-var.c
new file mode 100644
index 0000000..ea8df7b
--- /dev/null
+++ b/test/CodeGen/extern-block-var.c
@@ -0,0 +1,6 @@
+// RUN: clang %s -emit-llvm
+
+int f() {
+  extern int a;
+  return a;
+}