Latest changes in 1.0.12 broke Mesa's xvmc gallium driver build

The following commit broke Mesa's xvmc gallium driver build, since that references in XvMCCreateContex also XvQueryAdaptors, XvFreeAdaptorInfo and XvFreeAdaptorInfo

commit dd9ae037 Author: Adam Jackson ajax@redhat.com Date: Tue Jul 23 15:28:50 2019 -0400

pkgconfig: Remove xv from xvmc.pc