Sort all of Clang's files under 'lib', and fix up the broken headers

uncovered.

This required manually correcting all of the incorrect main-module
headers I could find, and running the new llvm/utils/sort_includes.py
script over the files.

I also manually added quite a few missing headers that were uncovered by
shuffling the order or moving headers up to be main-module-headers.

llvm-svn: 169237

clang/lib/Frontend/ASTMerge.cpp

@@ -7,12 +7,12 @@
 //
 //===----------------------------------------------------------------------===//
 #include "clang/Frontend/ASTUnit.h"
-#include "clang/Frontend/CompilerInstance.h"
-#include "clang/Frontend/FrontendActions.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/ASTDiagnostic.h"
 #include "clang/AST/ASTImporter.h"
 #include "clang/Basic/Diagnostic.h"
+#include "clang/Frontend/CompilerInstance.h"
+#include "clang/Frontend/FrontendActions.h"
 
 using namespace clang;