[Tests] Add missing include (NFC)

Fix one more missing include in a unit test after
983565a6fe4a9f40c7caf82b65c650c20dbcc104.

diff --git a/llvm/unittests/Support/TypeTraitsTest.cpp b/llvm/unittests/Support/TypeTraitsTest.cpp
index bd21343..734e50a 100644 (file)
--- a/llvm/unittests/Support/TypeTraitsTest.cpp
+++ b/llvm/unittests/Support/TypeTraitsTest.cpp
@@ -6,6 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/FunctionExtras.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/PointerIntPair.h"