* Make SPI work with 64 bit counters

Fix GET DIAGNOSTICS
Remove the earlier introduced SPI_processed64 variable

This includes the following upstream patches:
https://github.com/greenplum-db/gpdb/commit/23a27b039d94ba359286694831eafe03cd970eef
https://github.com/greenplum-db/gpdb/commit/f3f3aae4b7841f4dc51129691a7404a03eb55449
https://github.com/greenplum-db/gpdb/commit/ab737f6ba9fc0a26d32a95b115d5cd0e24a63191

The https://github.com/greenplum-db/gpdb/commit/74a379b984d4df91acec2436a16c51caee3526af
is not yet included, because repalloc_huge() is not yet backported.