Implemented sending buffer files in QBluetoothTransferReply QNX

QTemporaryFile did not work since it created temporary file
in the app folder, which was not accessible for sending and
sharing the file.

Task-number: QTBUG-32742

Change-Id: Icf3f30e800976916d3e82a928d04143757bf9afe
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>