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>
Fix possible case of uninstalling whole windows.

Task-number: QTIFW-511

In case we couldn't read the .dat file or the config file,
target dir will return the path the application was started.
Now we bail out early if one of the files is missing. Fixes
also some outdated code mess when we switched from a single
binary maintenance tool to the split binary version.

Change-Id: I4c70ac4ca63142873ed1521df47d74331669b576
Reviewed-by: Kai Koehne <kai.koehne@digia.com>
Reviewed-by: Niels Weber <niels.weber@digia.com>