pg_upgrade fix for connection testing

The attached, applied patch changes pg_upgrade:  now that it uses -w in
pg_ctl, remove loop that retried testing the connection;  also
restructure the libpq connection code.

This patch also removes the unused variable postmasterPID and fixes a
libpq PQconn structure leak that was in the testing loop.

Yeah, I got a fix into that patch.  ;-)

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +