this is QMakeEvaluatorHandler, but derived from QMakeParserHandler.
the idea is that the parser can be used stand-alone, while the evaluator
needs the parser as well.
we will need it in QMakeGlobals as well, so put it there, as that is the
most central place.

Change-Id: I6ee46c0e4b2e044bf3bfc6e4235b53525ddfc875
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>