qttest_p4.prf was added as a convenience for Qt's own autotests in Qt4.
It enables various crufty undocumented magic, of dubious value.
Stop using it, and explicitly enable the things from it which we want.
Change-Id: I7c1ffe9c8c294dbdc988e1582e580b1ed3f4593e
Reviewed-by: Jason McDonald <jason.mcdonald@nokia.com>