Re: MesaLib: build VDPAU support if it's available.

[David Shao <davshao%gmail.com@localhost>]

At some point, at least by mesa 17.0.0, these additions to
the PLIST will no longer be valid.

+${PLIST.vdpau}lib/dri/gallium_drv_video.la
+${PLIST.vdpau}lib/dri/gallium_drv_video.so

This is because of the commit
[Mesa-dev] st/va: hardlink driver instances to gallium_drv_video.so

https://patchwork.freedesktop.org/patch/82662/

What happens at least with latest mesa 17.0.0,
possibly as early as 12, is that other drivers simply are
relinks, as can be seen if building mesa 17.0.0.
The PLIST should actually contain something like:

${PLIST.vdpau}lib/dri/nouveau_drv_video.so
${PLIST.vdpau}lib/dri/r600_drv_video.so
${PLIST.vdpau}lib/dri/radeonsi_drv_video.so

There appear to be no corresponding .la files.

Also /usr/pkg/lib/dri is a mismatch for libva.pc's
current value of
driverdir=/usr/pkg/lib/xorg/modules/dri
Either libva's
--with-drivers-path=[path]
or MesaLib's
--with-va-libdir
configure option should be changed to match.

gmake[5]: Nothing to be done for 'install-exec-am'.
 ../../../../bin/install-sh -c -d
'/usr/pkgsrc/graphics/MesaLib/work/.destdir/usr/pkg/lib/dri'
 /bin/sh ../../../../libtool   --mode=install /usr/bin/install -c -o
root -g wheel   gallium_drv_video.la
'/usr/pkgsrc/graphics/MesaLib/work/.destdir/usr/pkg/lib/dri'
libtool: install: /usr/bin/install -c -o root -g wheel
.libs/gallium_drv_video.so
/usr/pkgsrc/graphics/MesaLib/work/.destdir/usr/pkg/lib/dri/gallium_drv_video.so
libtool: install: /usr/bin/install -c -o root -g wheel
.libs/gallium_drv_video.lai
/usr/pkgsrc/graphics/MesaLib/work/.destdir/usr/pkg/lib/dri/gallium_drv_video.la
libtool: install: warning: remember to run `libtool --finish /usr/pkg/lib/dri'
/usr/pkg/bin/gmake  install-data-hook
gmake[6]: Entering directory
'/usr/pkgsrc/graphics/MesaLib/work/mesa-17.0.0/src/gallium/targets/va'
for i in nouveau r600 radeonsi; do                                  \
    ln -f /usr/pkgsrc/graphics/MesaLib/work/.destdir/usr/pkg/lib/dri/gallium_drv_video.so
               \
          /usr/pkgsrc/graphics/MesaLib/work/.destdir/usr/pkg/lib/dri/${i}_drv_video.so;
                \
done;                                                           \