C++: Always remove NumericLiterals when removing the AST.

Contrary to StringLiterals, keeping them around is unnecessary.

Change-Id: Idc1967c125e1373e69ce4c7640328d323a84ec14
Reviewed-on: http://codereview.qt.nokia.com/3395
Reviewed-by: Roberto Raggi <roberto.raggi@nokia.com>

src/libs/cplusplus/CppDocument.h

@@ -335,7 +335,6 @@ private:
     QAtomicInt _keepSourceAndASTCount;
     unsigned _revision;
     unsigned _editorRevision;
-    bool _fastCheck;
 
     friend class Snapshot;
 };