Unexpected runtime output about biscuit

[grodranlorth]

Biscuit's modified Go runtime prints the "POOF" message (see biscuit/src/runtime/os_linux.go:3133). The runtime prints "POOF" each time it calls munmap() to remind me to fix munap() to not leak pages, as it currently does.

Only a few Kb of memory should be leaked this way, since the runtime only unmaps the old mark bitmaps. Once the size of the kernel heap stabilizes or reaches its max size, the runtime won't print POOF anymore. Thus the POOFs should go away if you run your program a couple times.