Qt: Fix build with Qt < 4.8

Change-Id: I13d4addb16c5c2790703feb63666367d39f36682
Reviewed-on: https://code.wireshark.org/review/5039
Reviewed-by: Michal Labedzki <michal.labedzki@tieto.com>
Translations: Update Polish translation

Still not complete, but almost complete.

Change-Id: I6e793c4f6648b423a42841347d22073c0b079767
Reviewed-on: https://code.wireshark.org/review/5040
Reviewed-by: Michal Labedzki <michal.labedzki@tieto.com>