This is necessary to handle Qt 5 moving mkspecs out of unsupported.

Task-number: QTCREATORBUG-6862
Change-Id: I193e3d16467773a2a714ef44f8d441d2d2395801
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>
Reviewed-by: Tobias Hunger <tobias.hunger@nokia.com>