Enable build on all supported linux platforms.

The build did not work when configuring to linux-g++-64,
although the platform is supported.

Task-number: QTBUG-41918
Change-Id: If2c8a5722d7d6b0ca28a99763531d8ffd9534de7
Reviewed-by: Andras Becsi <andras.becsi@digia.com>
Reviewed-by: Zeno Albisser <zeno.albisser@digia.com>