scripts: add possibility to customize some features
scripts: add possibility to customize some features

On Travis macOS VM, sanitizer works extremely slow, which leads to
timeouts while trying to run tests.

Also, qdoc is missing from the HomeBrew's Qt.

Change-Id: Idc9cec58531eeca7b5cd46f21ba4afed21e76620
Reviewed-by: Qbs CI Bot <94eb2064b2abdc395eb337a66643921d92d5d1fb@weickelt.de>
Reviewed-by: Richard Weickelt <320bca71fc381a4a025636043ca86e734e31cf8b@weickelt.de>
Reviewed-by: Christian Kandeler <3aa99dcdd3f0cac61fb81c2a11771c0cc2497607@qt.io>

qt-labs/qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qt-labs/qbs,qt-labs/qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qt-labs/qbs