SUSE-RU-2019:2715-1 Recommended update for xen

This update for xen to version 4.12.1 fixes the following issues: - Fixed an issue which made Xen crash on AMD ROME based machines bsc1135799. - Xenpvnetboot is now ported correctly to Python 3 bsc1138563. - Added code to change LIBXLHOTPLUGTIMEOUT at runtime bsc1120095. The included README has...