don't unnecessarily confuse qt creator

our CONFIG+=build_pass hack has the side effect that qmake does not emit
the calling command line to the makefile, which makes creator unable to
detect the build. so revert the hack as soon as it did its deed.

Task-number: QTBUG-34788
Change-Id: I4c0fd28d661ca5049f31d5405e84525efb12fd4e
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>