BUG #1008: fe-misc.c has an ifdef for HAVE_POLL, should be HAVE_POLL_H

The following bug has been logged online:

Bug reference:      1008
Logged by:          Peter Herndon
Email address:      tpherndon@mindspring.com
PostgreSQL version: 7.4
Operating system:   Mac OS X 10.3.1
Description:        fe-misc.c has an ifdef for HAVE_POLL, should be HAVE_POLL_H
Details:

With stock 7.4, configure options --prefix=/usr/local --with-rendezvous --with-openssl --with-includes=/sw/include
--with-libraries=/sw/lib,make failes on src/interfaces/libpq/fe-misc.c, complaining of undefined functions and
constantsin and around line 1011, pqSocketPoll function.  I poked around my config.log and config.status, and my OS,
andfound no trace of poll.h, instead I have select.h.  Yet the function was crashing the compile in lines looking for
poll.h. I looked at the source a bit more and noticed that the #ifdef was looking for HAVE_POLL, and that everything in
configure.*,as well as the top of fe-misc.c, was looking at HAVE_POLL_H.  So I changed line 1011 to HAVE_POLL_H and the
compilesucceeds.