lib: Free some memory in scripting subsystem at shutdown

lib: Free some memory in scripting subsystem at shutdown

Pre:
staticd: showing active allocations in memory group libfrr
staticd: memstats:  Scripting                     :     16 * (variably sized)
staticd: memstats:  Hash                          :      2 * (variably sized)
staticd: memstats:  Hash Bucket                   :      8 *         32
staticd: memstats:  Hash Index                    :      1 * (variably sized)
staticd: memstats:  Link List                     :      1 *         40
staticd: memstats:  Link Node                     :      1 *         24
staticd: showing active allocations in memory group logging subsystem
staticd: memstats:  log file target               :      1 *         88
staticd: showing active allocations in memory group staticd

Post:
staticd: showing active allocations in memory group libfrr
staticd: showing active allocations in memory group logging subsystem
staticd: memstats:  log file target               :      1 *         88
staticd: showing active allocations in memory group staticd

Signed-off-by: Donald Sharp <sharpd@nvidia.com>