HPCC-10646 Warning: case label value is less than minimum value for type

Change Thread class char (implicit used as TinyInt) type datamembers to int.
Change related functions parameter from char to int.

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>
Merge pull request #5336 from AttilaVamos/HPCC-10646-fix

HPCC-10646 Warning: case label value is less than minimum value for type

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>