Add missing #include found by modules buildbot.

llvm-svn: 230532

clang/include/clang/Sema/CodeCompleteConsumer.h

@@ -17,6 +17,7 @@
 #include "clang/AST/CanonicalType.h"
 #include "clang/AST/Type.h"
 #include "clang/Sema/CodeCompleteOptions.h"
+#include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Allocator.h"