Handling of QT_TIZEN_EMULATOR define.

Used instead of deprecated Q_OS_LINUX_TIZEN_SIMULATOR.

Change-Id: I70cb440c5916a7fd712f66142ee133e0d5b64a42
Reviewed-by: Jarosław Staniek <staniek@kde.org>
Reviewed-by: Leon Anavi <leon@anavi.org>