HPCC-8683 Problems with PLUGIN attribute on a service definition

Fix a spurious warning when using PLUGIN attribute, and ensure that the
default plugins location is on the libpath for linking to make life easier.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
HPCC-8950 Control:activeQueries crashes a stand alone roxie server instance

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #4089 from richardkchapman/roxie-activequeries

HPCC-8950 Control:activeQueries crashes a stand alone roxie server insta...

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>
Merge pull request #4049 from richardkchapman/plugin-resolve

HPCC-8683 Problems with PLUGIN attribute on a service definition

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>
HPCC-8928 Optimize a few minor uses of NOT(expression)

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>