add support for ref counts to memory allocator.

mark and sweep, stop the world garbage collector
(intermediate step in the way to ref counting).
can run pretty with an explicit gc after each file.

R=r
DELTA=502  (346 added, 143 deleted, 13 changed)
OCL=20630
CL=20635
12 files changed
tree: ae9d666b764532276b207e1125d30252716ab014
  1. doc/
  2. include/
  3. lib/
  4. pkg/
  5. src/
  6. test/
  7. usr/