Exclude qtconcurrent tests via .pro files.

Exclude qtconcurrent tests via .pro files.

If Qt is built without QtConcurrent, the relevant autotests should be
excluded from the build, rather than building empty tests that appear
to pass and thus produce confusing test results.

Change-Id: I43bafcb0ffa42e8981bec4e27bf6a23a28d86df9
Reviewed-on: http://codereview.qt-project.org/6395
Reviewed-by: Morten Johan Sørvig <morten.sorvig@nokia.com>
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>