Verify that code-completion is at least a little bit robust against inclusion of missing headers

llvm-svn: 86551
diff --git a/clang/test/Index/code-completion.cpp b/clang/test/Index/code-completion.cpp
index 875c746..14129cb 100644
--- a/clang/test/Index/code-completion.cpp
+++ b/clang/test/Index/code-completion.cpp
@@ -1,5 +1,5 @@
 // Code-completion through the C interface
-
+#include "nonexistent_header.h"
 struct X {
   int member;
 };