Remove UDP signalling code intended to work around OS X bug
Remove UDP signalling code intended to work around OS X bug

The UPD signalling code was added due to a bug in the pthreads code
in OS X 10.6 Snow Leopard which prevent pthread_cond_timedwait() to
work as intended. This version of the OS was discontinued in 2011
so it's time to retire this work around. OS X is not a supported
GPDB platform and as such we only make a best effort to run it on
the currently latest version.

In the process also make OS X use _timedwait() and not the relative
function for simplicity.

jmcatamney/gpdb,lintzc/gpdb,ashwinstar/gpdb,edespino/gpdb,Quikling/gpdb,50wu/gpdb,greenplum-db/gpdb,lintzc/gpdb,rvs/gpdb,edespino/gpdb,rvs/gpdb,janebeckman/gpdb,yuanzhao/gpdb,50wu/gpdb,rvs/gpdb,kaknikhil/gpdb,kaknikhil/gpdb,adam8157/gpdb,lintzc/gpdb,rvs/gpdb,Quikling/gpdb,edespino/gpdb,cjcjameson/gpdb,cjcjameson/gpdb,Chibin/gpdb,kaknikhil/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,cjcjameson/gpdb,lintzc/gpdb,xinzweb/gpdb,jmcatamney/gpdb,janebeckman/gpdb,Quikling/gpdb,ashwinstar/gpdb,janebeckman/gpdb,Chibin/gpdb,ashwinstar/gpdb,lisakowen/gpdb,Chibin/gpdb,edespino/gpdb,Chibin/gpdb,50wu/gpdb,kaknikhil/gpdb,lintzc/gpdb,Chibin/gpdb,cjcjameson/gpdb,lintzc/gpdb,Chibin/gpdb,yuanzhao/gpdb,xinzweb/gpdb,Chibin/gpdb,adam8157/gpdb,janebeckman/gpdb,greenplum-db/gpdb,edespino/gpdb,xinzweb/gpdb,Quikling/gpdb,rvs/gpdb,adam8157/gpdb,jmcatamney/gpdb,kaknikhil/gpdb,janebeckman/gpdb,Quikling/gpdb,jmcatamney/gpdb,rvs/gpdb,xinzweb/gpdb,ashwinstar/gpdb,kaknikhil/gpdb,xinzweb/gpdb,Quikling/gpdb,cjcjameson/gpdb,Quikling/gpdb,edespino/gpdb,greenplum-db/gpdb,janebeckman/gpdb,yuanzhao/gpdb,ashwinstar/gpdb,lintzc/gpdb,greenplum-db/gpdb,edespino/gpdb,janebeckman/gpdb,adam8157/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,edespino/gpdb,edespino/gpdb,cjcjameson/gpdb,adam8157/gpdb,50wu/gpdb,xinzweb/gpdb,Chibin/gpdb,lisakowen/gpdb,lisakowen/gpdb,Quikling/gpdb,50wu/gpdb,Chibin/gpdb,rvs/gpdb,adam8157/gpdb,yuanzhao/gpdb,greenplum-db/gpdb,yuanzhao/gpdb,lisakowen/gpdb,cjcjameson/gpdb,lisakowen/gpdb,lisakowen/gpdb,jmcatamney/gpdb,50wu/gpdb,jmcatamney/gpdb,rvs/gpdb,Quikling/gpdb,lintzc/gpdb,cjcjameson/gpdb,lisakowen/gpdb,yuanzhao/gpdb,edespino/gpdb,jmcatamney/gpdb,yuanzhao/gpdb,yuanzhao/gpdb,rvs/gpdb,Chibin/gpdb,xinzweb/gpdb,yuanzhao/gpdb,xinzweb/gpdb,yuanzhao/gpdb,janebeckman/gpdb,kaknikhil/gpdb,janebeckman/gpdb,greenplum-db/gpdb,rvs/gpdb,50wu/gpdb,adam8157/gpdb,greenplum-db/gpdb,janebeckman/gpdb,adam8157/gpdb,kaknikhil/gpdb,lisakowen/gpdb,ashwinstar/gpdb,lintzc/gpdb,kaknikhil/gpdb,cjcjameson/gpdb,cjcjameson/gpdb,50wu/gpdb,kaknikhil/gpdb,Quikling/gpdb