Make EGL optional since it's use in virglrenderer isn't always
compatible with drivers on linux, for example nVidia does not
provide a GBM implementation (used by virgl_egl*) with their
linux drivers.
Signed-off-by: Joe M. Kniss <djmk@google.com>
v2: Fix typo (Dave)
(still would much rather this was done at runtime as well)
Signed-off-by: Dave Airlie <airlied@redhat.com>