meson: Allow building glvnd with EGL and non-dri based GLX

Because meson mirrors the auototools logic, it needs the same changes to
allow building glvnd based egl.

v2: - change if to elif (Eric)

Signed-off-by: Dylan Baker <dylanx.c.baker@intel.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Acked-by: Emil Velikov <emil.velikov@collabora.com>
1 file changed