With modularized Qt, using QT_CONFIG is dangerous, because the behavior
changes depending on the order in which modules are qmake'd.
For example, an autotest doing:
contains(QT_CONFIG,svg):QT += svg
...will depend on libQtSvg if (and only if) the autotest is qmake'd
_after_ qtsvg is qmake'd.
This makes the tested functionality unpredictable.
Also, if the above example occurs within qtbase, it causes the test to
sometimes have a circular dependency: if qtsvg is qmake'd before the
test is qmake'd, the test in qtbase depends on qtsvg which depends on
qtbase.
Tests must avoid functionality tests via QT_CONFIG except where all the
tested modules are dependencies of the current module.
Usage of QT_CONFIG with qt3support was entirely removed since Qt5
will not retain qt3support.
Reviewed-by: Jason McDonald
Change-Id: I5a5013b3ec7e1f38fb78864763c9e7586c15e70b
173099696f