Qt5: Fixes for building Qt5 on master

Removing the version preference in the conf files.
Adding BBMASK for mesa and qtbase from meta-fsl-arm.

Signed-off-by: Sujith H <Sujith_Haridasan@mentor.com>
Merge pull request #66 from sharidas/qt5-master-fixes

Qt5: Fixes for building Qt5 on master