setup-qt: fix parsing of qmake's output
setup-qt: fix parsing of qmake's output

Current Qt5 "qmake -query" output wasn't parsed properly.
Also, now we don't run over the whole output for every variable
we're interested in.

Change-Id: I6268b61ce33211d3060dbd31e302654612b641d9
Reviewed-by: Christian Kandeler <3aa99dcdd3f0cac61fb81c2a11771c0cc2497607@digia.com>

Distrotech/qbs,villytiger/qbs,Distrotech/qbs,gatzka/qt-labs-qbs,qtproject/qt-labs-qbs,Distrotech/qbs,qtproject/qt-labs-qbs,qt-labs/qbs,Distrotech/qbs,qt-labs/qbs,villytiger/qbs,Distrotech/qbs,qtproject/qt-labs-qbs,villytiger/qbs,qt-labs/qbs,gatzka/qt-labs-qbs,gatzka/qt-labs-qbs,gatzka/qt-labs-qbs,Distrotech/qbs,gatzka/qt-labs-qbs,qt-labs/qbs,villytiger/qbs,villytiger/qbs,gatzka/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,villytiger/qbs,qt-labs/qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,qt-labs/qbs,Distrotech/qbs