Remove Diagnostic.h include from Preprocessor.h.

- Move the offending methods out of line and fix transitive includers.
- This required changing an enum in the PPCallback API into an unsigned.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@149782 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Rewrite/HTMLRewrite.cpp b/lib/Rewrite/HTMLRewrite.cpp
index beb8985..77c9969 100644
--- a/lib/Rewrite/HTMLRewrite.cpp
+++ b/lib/Rewrite/HTMLRewrite.cpp
@@ -17,6 +17,7 @@
 #include "clang/Rewrite/HTMLRewrite.h"
 #include "clang/Lex/TokenConcatenation.h"
 #include "clang/Lex/Preprocessor.h"
+#include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/SourceManager.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/OwningPtr.h"