HPCC-8863 Fix cores generating independent dictionaries.

This also fixes a bug where a FEW attribute on an expression that
was generated as a global could be mis-interpreted as a FEW attribute
on a GLOBAL() operator.

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #4014 from ghalliday/issue8863

HPCC-8863 Fix cores generating independent dictionaries.

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>