Make pgstatindex respond to cancel interrupts.
Make pgstatindex respond to cancel interrupts.

A similar problem for pgstattuple() was fixed in April of 2010 by commit
33065ef8bc52253ae855bc959576e52d8a28ba06, but pgstatindex() seems to have
been overlooked.

Back-patch all the way, as with that commit, though not to 7.4 through
8.1, since those are now EOL.

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