initial import of libxshmfence-1.3.3

merge libXext 1.3.5, libbXmu 1.1.4, libXrender 1.0.1, libxkbfile 1.1.1 and
libxshmfence 1.3.1.

initial import of libxshmfence-1.3.1

sync from pkgsrc:

> libxshmfence: improve performance of semaphore backend. Bump rev.
>
> It used more locking than necessary. We only need two semaphores.
> One to tell waiters to wake up and one to let the last waiter that
> wakes up notify xshmfence_trigger() it may now return.

initial import of libxshmfence-1.3

port across patches from pkgsrc.

initial import of libxshmfence-1.2