HPCC-11937 Fix race condition in smart join

HPCC-11953 Throw error when RIGHT rows would be lost

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Have these been removed as your point is that locking at this stage is too late and that it needs to occur before the call... but they're all inline so... I don't understand.