[clang-format] Make header self-contained

These includes were removed in 426e694

Author: d0k

clang/lib/Format/FormatInternal.h

@@ -15,6 +15,11 @@
 #ifndef LLVM_CLANG_LIB_FORMAT_FORMATINTERNAL_H
 #define LLVM_CLANG_LIB_FORMAT_FORMATINTERNAL_H
 
+#include "clang/Basic/LLVM.h"
+#include "clang/Format/Format.h"
+#include "clang/Tooling/Core/Replacement.h"
+#include <utility>
+
 namespace clang {
 namespace format {
 namespace internal {