[PATCH] Free Thread Interpreter Pool During Shutdown

[Chromatic]

I'm running Valgrind:

$ valgrind --num-callers=20 --leak-check=full --show-reachable=yes
parrot --leak-test t/pmc/ref_12.pasm

==10213== 60 bytes in 1 blocks are still reachable in loss record 1 of 6
==10213== at 0x40206D5: calloc (vg_replace_malloc.c:279)
==10213== by 0x41E822E: mem_sys_allocate_zeroed (memory.c:79)
==10213== by 0x426C3DD: pt_add_to_interpreters (thread.c:1276)
==10213== by 0x4268CEB: Parrot_init_events (events.c:313)
==10213== by 0x41E5D2B: make_interpreter (inter_create.c:245)
==10213== by 0x424300E: Parrot_new (embed.c:48)
==10213== by 0x804A433: main (main.c:514)

Here's a patch for that. Any objections?

I know that everything gets freed with the process ends, but by clearing
these "leaks" out of the report makes it much more useful for finding actual
leaks.

-- c