Remove unused compiler flags from mapreduce Makefile
Remove unused compiler flags from mapreduce Makefile

GPMapreduce isn't threaded so -pthreads is a noop causing annoying
warning messages in clang.

zaksoup/gpdb,rubikloud/gpdb,royc1/gpdb,xuegang/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,janebeckman/gpdb,edespino/gpdb,randomtask1155/gpdb,cjcjameson/gpdb,foyzur/gpdb,tangp3/gpdb,xinzweb/gpdb,lisakowen/gpdb,yuanzhao/gpdb,janebeckman/gpdb,50wu/gpdb,lintzc/gpdb,lintzc/gpdb,jmcatamney/gpdb,foyzur/gpdb,xinzweb/gpdb,rubikloud/gpdb,jmcatamney/gpdb,ahachete/gpdb,atris/gpdb,adam8157/gpdb,adam8157/gpdb,edespino/gpdb,kaknikhil/gpdb,cjcjameson/gpdb,chrishajas/gpdb,yuanzhao/gpdb,50wu/gpdb,50wu/gpdb,cjcjameson/gpdb,rvs/gpdb,lintzc/gpdb,xuegang/gpdb,xuegang/gpdb,jmcatamney/gpdb,Chibin/gpdb,Quikling/gpdb,greenplum-db/gpdb,kaknikhil/gpdb,chrishajas/gpdb,Quikling/gpdb,ashwinstar/gpdb,chrishajas/gpdb,xinzweb/gpdb,zaksoup/gpdb,yuanzhao/gpdb,rvs/gpdb,ahachete/gpdb,xuegang/gpdb,xuegang/gpdb,greenplum-db/gpdb,yuanzhao/gpdb,foyzur/gpdb,0x0FFF/gpdb,zaksoup/gpdb,rvs/gpdb,CraigHarris/gpdb,janebeckman/gpdb,randomtask1155/gpdb,royc1/gpdb,atris/gpdb,50wu/gpdb,lpetrov-pivotal/gpdb,kaknikhil/gpdb,greenplum-db/gpdb,foyzur/gpdb,yuanzhao/gpdb,randomtask1155/gpdb,lisakowen/gpdb,atris/gpdb,rvs/gpdb,chrishajas/gpdb,rvs/gpdb,xuegang/gpdb,CraigHarris/gpdb,rubikloud/gpdb,zaksoup/gpdb,lpetrov-pivotal/gpdb,lintzc/gpdb,0x0FFF/gpdb,janebeckman/gpdb,CraigHarris/gpdb,edespino/gpdb,CraigHarris/gpdb,xinzweb/gpdb,atris/gpdb,royc1/gpdb,greenplum-db/gpdb,kaknikhil/gpdb,lintzc/gpdb,greenplum-db/gpdb,0x0FFF/gpdb,rvs/gpdb,lpetrov-pivotal/gpdb,foyzur/gpdb,kaknikhil/gpdb,greenplum-db/gpdb,xinzweb/gpdb,xinzweb/gpdb,Chibin/gpdb,lintzc/gpdb,lintzc/gpdb,yuanzhao/gpdb,cjcjameson/gpdb,yuanzhao/gpdb,Quikling/gpdb,Quikling/gpdb,tangp3/gpdb,tangp3/gpdb,adam8157/gpdb,yuanzhao/gpdb,lpetrov-pivotal/gpdb,cjcjameson/gpdb,ahachete/gpdb,rvs/gpdb,ashwinstar/gpdb,cjcjameson/gpdb,lisakowen/gpdb,yuanzhao/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,xinzweb/gpdb,adam8157/gpdb,ahachete/gpdb,50wu/gpdb,adam8157/gpdb,xuegang/gpdb,Quikling/gpdb,xuegang/gpdb,jmcatamney/gpdb,edespino/gpdb,CraigHarris/gpdb,Chibin/gpdb,ashwinstar/gpdb,CraigHarris/gpdb,adam8157/gpdb,edespino/gpdb,atris/gpdb,edespino/gpdb,xinzweb/gpdb,rvs/gpdb,randomtask1155/gpdb,Quikling/gpdb,lisakowen/gpdb,Chibin/gpdb,Quikling/gpdb,0x0FFF/gpdb,Quikling/gpdb,royc1/gpdb,ahachete/gpdb,tangp3/gpdb,tangp3/gpdb,lintzc/gpdb,Quikling/gpdb,lpetrov-pivotal/gpdb,tangp3/gpdb,kaknikhil/gpdb,zaksoup/gpdb,xuegang/gpdb,edespino/gpdb,cjcjameson/gpdb,janebeckman/gpdb,chrishajas/gpdb,chrishajas/gpdb,rvs/gpdb,0x0FFF/gpdb,randomtask1155/gpdb,atris/gpdb,kaknikhil/gpdb,lpetrov-pivotal/gpdb,Quikling/gpdb,greenplum-db/gpdb,50wu/gpdb,cjcjameson/gpdb,rvs/gpdb,Chibin/gpdb,ahachete/gpdb,0x0FFF/gpdb,jmcatamney/gpdb,Chibin/gpdb,adam8157/gpdb,kaknikhil/gpdb,atris/gpdb,tangp3/gpdb,chrishajas/gpdb,jmcatamney/gpdb,rubikloud/gpdb,cjcjameson/gpdb,kaknikhil/gpdb,foyzur/gpdb,rubikloud/gpdb,CraigHarris/gpdb,adam8157/gpdb,cjcjameson/gpdb,jmcatamney/gpdb,lisakowen/gpdb,janebeckman/gpdb,50wu/gpdb,rubikloud/gpdb,Chibin/gpdb,janebeckman/gpdb,CraigHarris/gpdb,lisakowen/gpdb,lpetrov-pivotal/gpdb,edespino/gpdb,royc1/gpdb,janebeckman/gpdb,yuanzhao/gpdb,lisakowen/gpdb,ashwinstar/gpdb,lpetrov-pivotal/gpdb,ashwinstar/gpdb,lintzc/gpdb,randomtask1155/gpdb,janebeckman/gpdb,ahachete/gpdb,edespino/gpdb,zaksoup/gpdb,rubikloud/gpdb,chrishajas/gpdb,atris/gpdb,0x0FFF/gpdb,Chibin/gpdb,foyzur/gpdb,ahachete/gpdb,janebeckman/gpdb,royc1/gpdb,CraigHarris/gpdb,Chibin/gpdb,0x0FFF/gpdb,randomtask1155/gpdb,royc1/gpdb,50wu/gpdb,randomtask1155/gpdb,edespino/gpdb,rubikloud/gpdb,foyzur/gpdb,zaksoup/gpdb,Chibin/gpdb,kaknikhil/gpdb,greenplum-db/gpdb,tangp3/gpdb,royc1/gpdb,zaksoup/gpdb,lisakowen/gpdb