multimedia/libvdpau-va-gl: Deprecate port
- Fails to build with the upcoming new cmake version.
- No new releases in more than 10 years.
- VDPAU has been uperceded by VAAPI
PR: 298620
MFH: 2026Q3
(cherry picked from commit 8ae0e401ad1fafee4d100d7f3439d9d8477e6c19)