Tests: Rename test function in tst_lexer.cpp

...to a more generic name since it is not any more limited to doxygen.

Change-Id: I0fca5dab9b5ab8850b2cfba5758b51f0451c199d
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>
CppEditor: Use TypeHierarchyBuilder in FunctionHelper::overrides

...instead going the way over CppClass. This makes
FunctionHelper::overrides independent of the cppeditor plugin.

Change-Id: Ifaedb94da1f67b3876e06cce9e745aaf3c1050a7
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>