meson: Do not require libdrm for DRI2 on hurd

Cc: 19.3 <mesa-stable@lists.freedesktop.org>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3231>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3231>
(cherry picked from commit 2fd85105c6b144d1f44e5faef33363e554b58455)
2 files changed