libdrm: port to Meson

libdrm: port to Meson

Drop the patch to install tests as the Meson build allows this.

Drop the patch to disable cunit as this predates recipe-specific-sysroots and
isn't required anymore.

As Meson always builds the test suite (instead of building before running it),
add a patch to fix compilation with musl.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>