xf86drm: add a non-sysfs version of drmGetDeviceNameFromFd2

Implement a generic drmGetDeviceNameFromFd2() to use on non-linux
systems without sysfs.

v2: remove min < base test as requested by Emil

Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Jonathan Gray <jsg@jsg.id.au>
1 file changed