move library-specific diagnostic headers into library private dirs.  Reduce
redundant #includes.  Patch by Anders Johnsen!


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@63271 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Lex/PPExpressions.cpp b/lib/Lex/PPExpressions.cpp
index 73d677f..3cba06f 100644
--- a/lib/Lex/PPExpressions.cpp
+++ b/lib/Lex/PPExpressions.cpp
@@ -20,7 +20,7 @@
 #include "clang/Lex/MacroInfo.h"
 #include "clang/Lex/LiteralSupport.h"
 #include "clang/Basic/TargetInfo.h"
-#include "clang/Basic/DiagnosticLex.h"
+#include "clang/Lex/LexDiagnostic.h"
 #include "llvm/ADT/APSInt.h"
 using namespace clang;