Clang: Avoid double reparsing

The document is now always reparsed after a change.

Change-Id: Iad1d9f78d98f75d5e873de35ac487a8dabc4fc4e
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@theqtcompany.com>

src/tools/clangbackend/ipcsource/translationunit.cpp

@@ -257,9 +257,6 @@ void TranslationUnit::createTranslationUnitIfNeeded() const
 
         updateIncludeFilePaths();
 
-        // We need to reparse to create the precompiled preamble, which will speed up further calls,
-        // e.g. clang_codeCompleteAt() dramatically.
-        reparseTranslationUnit();
 
         updateLastProjectPartChangeTimePoint();
     }