HPCC-10910 Ensure abort is checked before spawning a child

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPCC-10910 Check aborting after first attempt to connect to slave

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #5503 from ghalliday/issue10910

HPCC-10910 Ensure abort is checked before spawning a child

Reviewed-By: Jake Smith <jake.smith@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>