[PATCH xserver 0/2] Build poll emulation when needed and then use it

[Keith Packard]

 [PATCH xserver 1/2] os: Add poll emulation for mingw [v2]

Adam provided a patch which added poll emulation on top of
select. This takes that patch, modifies it slightly, and then builds
the code for platforms which don't have a native poll implementation
(like mingw). Finally, the patch provides a wrapper around either that
emulation or the real poll implementation in the xserver_poll.h file.

 [PATCH xserver 2/2] Switch poll() users to xserver_poll()

The second patch uses that wrapper everywhere the server currently
uses poll directly. I don't think this will actually help anything as
poll should be available on every system that would have used that
code. However, I did demonstrate that it all worked by disabling the
poll detection in configure.ac and building servers that used select
everywhere and poll nowhere.

With this in place, I believe we can merge the ospoll interfaces on
top and have the server run on every system that it used to run on.

-keith