[CFT] Mesa 18.1.0 update (mesa-libs, mesa-dri, libosmesa, clover)

[Jan Beich]

Mesa provides OpenGL/Vulkan drivers for Intel/AMD cards and also VAAPI/VDPAU
drivers for AMD cards. Recently, a new minor version was released. So far it
was only tested via drm-stable-kmod on 12.0-CURRENT. Can someone test on
FreeBSD < 11.2 for regressions? If you find any don't forget to attech
/var/log/Xorg.0.log and LIBGL_DEBUG=verbose output.

I'd like to land the update in 2 weeks.

# Apply
$ fetch -qo /tmp/mesa-18.1.0.diff 'https://bugs.freebsd.org/bugzilla/attachment.cgi?id=193545'
$ patch -Efsp0 -i /tmp/mesa-18.1.0.diff -d /usr/ports
$ make all deinstall install clean -C /usr/ports/graphics/mesa-libs
$ make all deinstall install clean -C /usr/ports/graphics/mesa-dri

# Undo
$ patch -REfsp0 -i /tmp/mesa-18.1.0.diff -d /usr/ports
$ make all deinstall install clean -C /usr/ports/graphics/mesa-libs
$ make all deinstall install clean -C /usr/ports/graphics/mesa-dri

# Testing examples
- graphics/mesa-demos: glxgears, eglgears_x11
- multimedia/mpv: --hwdec=auto (VAAPI/VDPAU EGL interop)
- www/firefox: gfx.webrender.all=true (GPU compositing)
- https://forums.freebsd.org/threads/unreal-engine-4.65300/