libdrm: upgrade to 2.4.59

* Refreshed installtests.patch
* Removed --enable-freedreno-experimental-api, since it is now enabled by
  default upstream

Tested on Snapdragon 600 with freedreno and X11.

Signed-off-by: Nicolas Dechesne <nicolas.dechesne@linaro.org>
Signed-off-by: Ross Burton <ross.burton@intel.com>