mesa: Support building without opengl

mesa: Support building without opengl

mesa can build certain things without opengl: most importantly vulkan
drivers.

Add comments on the dependencies between the packageconfigs. Also add
a few dependencies to packageconfigs. Modify default packageconfig to
do the reasonable thing based on distro features.

Add a backported patch to fix the build with --disable-opengl. Fix
do_install_append() so it works even if dri drivers are not built.

Signed-off-by: Jussi Kukkonen <jussi.kukkonen@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>