weston-wfits.so: support non-X environments

This also fixes the dependency on libxcb and libX11 symbols that
were previously and implicitly loaded during Weston's runtime.
Weston no longer links directly to X libraries (and appropriately so)
and thus no longer makes the symbols available to the weston-wfits.so
module when it's loaded.

Signed-off-by: U. Artie Eoff <ullysses.a.eoff@intel.com>