gdm: collective update

This update fixes the following issues for gdm:
- Change gdm-welcome.pamd source file to fix bnc#731867:
+ For some mysterious reason (external to the gdm package, as far as I can tell), the gdm account got locked on some systems in the past, and this made gdm simply hang on startup.
+ The gdm-welcome PAM service is only used for the gdm account in the gdm greeter session, so a fix to this issue is to disable the standard PAM account management in this gdm-welcome PAM service.
+ To that end, simply use pam_permit.so for account management in gdm-welcome instead of inclusing the usual common-account file.
- bnc#627575: Drop gdm-domain-logon.patch
- Remove support for gnome-patch-translation since there are not patches adding translations left: remove gnome-patch-translation BuildRequires and commented out calls to gnome-patch-translation-prepare and gnome-patch-translation-update.

Fixed bugs
bnc#627575
gdm-domain-logon.patch
bnc#731867
gdm hangs after Tumbleweed base update from 11.4 to 12.1
Selected Binaries
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