Each Linux distro takes a different spin on providing kernel's uapi
headers (especialy the *drm*.h).

You can get them with linux-headers, you can get them with libdrm.
Sometime you can even get them twice, from both sources.

Sometimes the headers match your kernel version, sometimes you end up
stuck with headers matching the kernel that the given release of the
distro came out with.

This makes things harder for code that does not depend on libdrm, as we
cannot have sane ./configure-time checks.

So let's define LOCAL_ version for FENCE and EXECBUFFER2_WB defines
until all the stable distros catch up (+/- some epsilon).

Cc: Petri Latvala <petri.latvala@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>