Add a clean target so that the root directory gets cleared of all the "configure" related files on a make clean
Add a clean target so that the root directory gets cleared of all
the "configure" related files on a make clean

zaksoup/gpdb,kaknikhil/gpdb,kaknikhil/gpdb,50wu/gpdb,tpostgres-projects/tPostgres,chrishajas/gpdb,janebeckman/gpdb,50wu/gpdb,xinzweb/gpdb,greenplum-db/gpdb,foyzur/gpdb,oberstet/postgres-xl,Chibin/gpdb,royc1/gpdb,atris/gpdb,royc1/gpdb,yazun/postgres-xl,0x0FFF/gpdb,jmcatamney/gpdb,kaknikhil/gpdb,lpetrov-pivotal/gpdb,yazun/postgres-xl,janebeckman/gpdb,zaksoup/gpdb,Chibin/gpdb,randomtask1155/gpdb,xinzweb/gpdb,yuanzhao/gpdb,ahachete/gpdb,rubikloud/gpdb,jmcatamney/gpdb,Postgres-XL/Postgres-XL,lpetrov-pivotal/gpdb,pavanvd/postgres-xl,adam8157/gpdb,lintzc/gpdb,royc1/gpdb,adam8157/gpdb,kmjungersen/PostgresXL,lintzc/gpdb,ashwinstar/gpdb,yuanzhao/gpdb,greenplum-db/gpdb,yuanzhao/gpdb,lisakowen/gpdb,Chibin/gpdb,cjcjameson/gpdb,ahachete/gpdb,zeroae/postgres-xl,jmcatamney/gpdb,adam8157/gpdb,arcivanov/postgres-xl,lisakowen/gpdb,oberstet/postgres-xl,edespino/gpdb,Postgres-XL/Postgres-XL,rubikloud/gpdb,snaga/postgres-xl,lpetrov-pivotal/gpdb,xuegang/gpdb,atris/gpdb,CraigHarris/gpdb,edespino/gpdb,rvs/gpdb,kmjungersen/PostgresXL,chrishajas/gpdb,xinzweb/gpdb,janebeckman/gpdb,kaknikhil/gpdb,janebeckman/gpdb,Quikling/gpdb,Postgres-XL/Postgres-XL,jmcatamney/gpdb,postmind-net/postgres-xl,oberstet/postgres-xl,xuegang/gpdb,jmcatamney/gpdb,randomtask1155/gpdb,ahachete/gpdb,postmind-net/postgres-xl,tangp3/gpdb,tpostgres-projects/tPostgres,royc1/gpdb,lintzc/gpdb,yuanzhao/gpdb,lisakowen/gpdb,kmjungersen/PostgresXL,Chibin/gpdb,postmind-net/postgres-xl,rvs/gpdb,atris/gpdb,yazun/postgres-xl,chrishajas/gpdb,xuegang/gpdb,pavanvd/postgres-xl,lpetrov-pivotal/gpdb,0x0FFF/gpdb,xinzweb/gpdb,ovr/postgres-xl,pavanvd/postgres-xl,zaksoup/gpdb,Chibin/gpdb,edespino/gpdb,lisakowen/gpdb,Chibin/gpdb,xuegang/gpdb,yuanzhao/gpdb,tangp3/gpdb,yuanzhao/gpdb,yazun/postgres-xl,lintzc/gpdb,lpetrov-pivotal/gpdb,randomtask1155/gpdb,techdragon/Postgres-XL,snaga/postgres-xl,xinzweb/gpdb,xinzweb/gpdb,xinzweb/gpdb,edespino/gpdb,ahachete/gpdb,randomtask1155/gpdb,0x0FFF/gpdb,cjcjameson/gpdb,postmind-net/postgres-xl,lisakowen/gpdb,Chibin/gpdb,tangp3/gpdb,foyzur/gpdb,0x0FFF/gpdb,zaksoup/gpdb,ahachete/gpdb,zaksoup/gpdb,cjcjameson/gpdb,janebeckman/gpdb,randomtask1155/gpdb,randomtask1155/gpdb,zeroae/postgres-xl,CraigHarris/gpdb,atris/gpdb,rvs/gpdb,arcivanov/postgres-xl,Quikling/gpdb,ovr/postgres-xl,ahachete/gpdb,janebeckman/gpdb,ashwinstar/gpdb,foyzur/gpdb,0x0FFF/gpdb,ashwinstar/gpdb,CraigHarris/gpdb,chrishajas/gpdb,CraigHarris/gpdb,rvs/gpdb,lintzc/gpdb,rvs/gpdb,chrishajas/gpdb,edespino/gpdb,snaga/postgres-xl,foyzur/gpdb,50wu/gpdb,cjcjameson/gpdb,zeroae/postgres-xl,yuanzhao/gpdb,ashwinstar/gpdb,50wu/gpdb,ovr/postgres-xl,arcivanov/postgres-xl,yuanzhao/gpdb,zaksoup/gpdb,ahachete/gpdb,rvs/gpdb,adam8157/gpdb,chrishajas/gpdb,rubikloud/gpdb,lisakowen/gpdb,Chibin/gpdb,arcivanov/postgres-xl,jmcatamney/gpdb,lintzc/gpdb,Quikling/gpdb,kmjungersen/PostgresXL,arcivanov/postgres-xl,xuegang/gpdb,tangp3/gpdb,techdragon/Postgres-XL,rvs/gpdb,xuegang/gpdb,tpostgres-projects/tPostgres,atris/gpdb,greenplum-db/gpdb,janebeckman/gpdb,snaga/postgres-xl,greenplum-db/gpdb,foyzur/gpdb,kaknikhil/gpdb,Postgres-XL/Postgres-XL,xuegang/gpdb,rubikloud/gpdb,adam8157/gpdb,yuanzhao/gpdb,foyzur/gpdb,cjcjameson/gpdb,tangp3/gpdb,Quikling/gpdb,foyzur/gpdb,xuegang/gpdb,lpetrov-pivotal/gpdb,kaknikhil/gpdb,rubikloud/gpdb,postmind-net/postgres-xl,royc1/gpdb,0x0FFF/gpdb,rubikloud/gpdb,zeroae/postgres-xl,kaknikhil/gpdb,edespino/gpdb,tpostgres-projects/tPostgres,rvs/gpdb,yuanzhao/gpdb,royc1/gpdb,xuegang/gpdb,atris/gpdb,yazun/postgres-xl,chrishajas/gpdb,techdragon/Postgres-XL,CraigHarris/gpdb,kaknikhil/gpdb,xinzweb/gpdb,atris/gpdb,techdragon/Postgres-XL,Quikling/gpdb,50wu/gpdb,tangp3/gpdb,chrishajas/gpdb,ashwinstar/gpdb,rvs/gpdb,Chibin/gpdb,zaksoup/gpdb,cjcjameson/gpdb,jmcatamney/gpdb,ovr/postgres-xl,rvs/gpdb,pavanvd/postgres-xl,ovr/postgres-xl,adam8157/gpdb,tangp3/gpdb,zaksoup/gpdb,Quikling/gpdb,cjcjameson/gpdb,Quikling/gpdb,oberstet/postgres-xl,lpetrov-pivotal/gpdb,ashwinstar/gpdb,lintzc/gpdb,0x0FFF/gpdb,adam8157/gpdb,adam8157/gpdb,snaga/postgres-xl,greenplum-db/gpdb,tangp3/gpdb,edespino/gpdb,janebeckman/gpdb,CraigHarris/gpdb,Quikling/gpdb,foyzur/gpdb,ashwinstar/gpdb,atris/gpdb,CraigHarris/gpdb,janebeckman/gpdb,Quikling/gpdb,arcivanov/postgres-xl,lpetrov-pivotal/gpdb,CraigHarris/gpdb,lisakowen/gpdb,50wu/gpdb,rubikloud/gpdb,pavanvd/postgres-xl,janebeckman/gpdb,lintzc/gpdb,kaknikhil/gpdb,Postgres-XL/Postgres-XL,ahachete/gpdb,edespino/gpdb,randomtask1155/gpdb,Quikling/gpdb,cjcjameson/gpdb,lisakowen/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,50wu/gpdb,royc1/gpdb,kmjungersen/PostgresXL,royc1/gpdb,edespino/gpdb,ashwinstar/gpdb,edespino/gpdb,greenplum-db/gpdb,rubikloud/gpdb,0x0FFF/gpdb,kaknikhil/gpdb,cjcjameson/gpdb,tpostgres-projects/tPostgres,lintzc/gpdb,Chibin/gpdb,randomtask1155/gpdb,techdragon/Postgres-XL,greenplum-db/gpdb,oberstet/postgres-xl,zeroae/postgres-xl,CraigHarris/gpdb,cjcjameson/gpdb,50wu/gpdb