Adds vmm block accounting by adding flags passed to the vmm block allocation routines labeling each as either heap, stack, cache, special heap, or special mmap. Adds an rstat for each.
This provides a nice, clean, useful breakdown of memory usage within the vmm region on Linux, where today's stats are misleadingly focused on committed memory despite reservations nearly doubling that amount on Linux.
Fixes #2574 (closed)