[PATCH] Make pollsets and pollcb implementation selectable

[Mladen Turk <mt...@apache.org>]

Hi,
Before committing the code please review
cause it pretty large.

Added apr_pollset_create_ex
with method enum that can be used to choose
non-default poll method.
If not supported it will automatically choose
the default one (default is what's now platform specific)
unless APR_POLLSET_NODEFAULT is added to the flag param.
On linux poll test passes with either epoll, poll or select,
and on mac with kqueue, poll or select.

I think I didn't make any breakage.
(Well didn't test the port.c)


Regards
-- 
^(TM)