Handle the case where EmitBlock might be called multiple times for the same block. Fixes PR3536.

llvm-svn: 64252
diff --git a/clang/test/CodeGen/vla.c b/clang/test/CodeGen/vla.c
index 2197ee1..beb928b 100644
--- a/clang/test/CodeGen/vla.c
+++ b/clang/test/CodeGen/vla.c
@@ -18,3 +18,14 @@
   int vla[x];
   return vla[x-1];
 }
+
+void
+f(int count)
+{
+ int a[count];
+
+  do {  } while (0);
+
+  if (a[0] != 3) {
+  }
+}