QtIFW

Revert "Make the auto tests available by default."

This reverts commit fca72823ea2a9c627e86d2fb769929999ed6fe43
to speed up compilation on slower systems. It introduces the
possibility to set an environment variable or pass BUILDTESTS
as argument to qmake to make the tests available.

Change-Id: Iab5846473bac2dddbec85b45a7a7ad70552171a4
Reviewed-by: Kai Koehne <kai.koehne@digia.com>