Was only around as opencl's pipe-loader wanted to link against xcb in
some cases.
Cc: Rob Clark <robclark@freedesktop.org>
Cc: Tom Stellard <thomas.stellard@amd.com>
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>