QNX: enable AudioCapture plugin.

This allows to use the QAudioRecorder API on QNX (and Blackberry), using
the low-latency audio plugin as backend.

Change-Id: I9bed7c01948a40f931f2a6b29c0f5cbfc99635bd
Reviewed-by: Rafael Roquetto <rafael.roquetto@kdab.com>
Reviewed-by: Thomas McGuire <thomas.mcguire@kdab.com>