package/weston: restore the freerdp backend

Now that we've switched to using FreeRDP from master, we can build weston's
FreeRDP backend again.

Propagate the new dependencies of FreeRDP.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>