st/dri: Check for kernel support before enabling fd sharing v2

st/dri: Check for kernel support before enabling fd sharing v2

The dri2 state tracker is checking for driver support before enabling
dri2ImageExtension version 7. This commit adds a check that also the
kernel driver supports fd sharing through prime.

Note that this adds a libdrm dependency on dri2.c.

v2: Removed unnecessary clamping of bool expression

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>