Add comment about the deadlock assertion in libmn.cpp
Use default stack in simple.c
posix_tls: value-initialize for managed type to mimic STL conventions
signal_cpualarm: actually support per-thread cpu alarms
cpuburn: don't run forever
various changes to allow the runtime to schedule over multiple kernel threads
Make sure all files bear the copyright notice, all code in previous commits are licensed GPLv3
libmn: don't use `allow_exit` to assert against a deadlock

using `allow_exit` in the `waiting_fiber()` loop didn't make
sense. if we are woken up, the proclet that set `allow_exit`
might have already been rescheduled. it only makes sense to
check it synchronously when the proc is entering the wait
state but even then it doesn't catch all cases of deadlock.

it's easier to just test if there are proclets waiting on
port IO when there are definitely no more proclets to run.
libmn: add an assert against a returned proclet being rescheduled
add primesieve in pipes + get termination correct in libmn version for benchmarking.