meson: use library() instead of shared_library().

This allows users to select the library type (static or shared)
using the Meson -Ddefault_library built-in option.

Issue: https://gitlab.freedesktop.org/mesa/drm/-/issues/45



Reviewed-by: Simon Ser <contact@emersion.fr>
Signed-off-by: Fang Tan <tanfang@uniontech.com>