Move multixid allocation out of critical section.
Move multixid allocation out of critical section.

It can fail if you run out of memory.

This call was added in 9.3, so backpatch to 9.3 only.

50wu/gpdb,yazun/postgres-xl,zeroae/postgres-xl,ashwinstar/gpdb,adam8157/gpdb,pavanvd/postgres-xl,greenplum-db/gpdb,adam8157/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,lisakowen/gpdb,techdragon/Postgres-XL,lisakowen/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,oberstet/postgres-xl,pavanvd/postgres-xl,ashwinstar/gpdb,pavanvd/postgres-xl,Postgres-XL/Postgres-XL,xinzweb/gpdb,oberstet/postgres-xl,xinzweb/gpdb,lisakowen/gpdb,greenplum-db/gpdb,adam8157/gpdb,jmcatamney/gpdb,lisakowen/gpdb,jmcatamney/gpdb,xinzweb/gpdb,50wu/gpdb,50wu/gpdb,greenplum-db/gpdb,adam8157/gpdb,zeroae/postgres-xl,50wu/gpdb,techdragon/Postgres-XL,ashwinstar/gpdb,greenplum-db/gpdb,lisakowen/gpdb,lisakowen/gpdb,adam8157/gpdb,yazun/postgres-xl,jmcatamney/gpdb,ashwinstar/gpdb,oberstet/postgres-xl,zeroae/postgres-xl,zeroae/postgres-xl,Postgres-XL/Postgres-XL,yazun/postgres-xl,Postgres-XL/Postgres-XL,oberstet/postgres-xl,greenplum-db/gpdb,50wu/gpdb,ovr/postgres-xl,50wu/gpdb,techdragon/Postgres-XL,yazun/postgres-xl,ashwinstar/gpdb,pavanvd/postgres-xl,pavanvd/postgres-xl,ovr/postgres-xl,xinzweb/gpdb,ashwinstar/gpdb,techdragon/Postgres-XL,yazun/postgres-xl,oberstet/postgres-xl,xinzweb/gpdb,xinzweb/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,adam8157/gpdb,Postgres-XL/Postgres-XL,ovr/postgres-xl,xinzweb/gpdb,50wu/gpdb,lisakowen/gpdb,adam8157/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,Postgres-XL/Postgres-XL,adam8157/gpdb,50wu/gpdb,zeroae/postgres-xl,xinzweb/gpdb,ovr/postgres-xl,techdragon/Postgres-XL,ovr/postgres-xl,jmcatamney/gpdb,lisakowen/gpdb