Compile fix: do not use composeMode() if QT_NO_IM is defined.

Change-Id: Ib0046657ba687e6427c67c7dce0d71ec3be87f48
Reviewed-by: Mitch Curtis <mitch.curtis@digia.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>