execve: other threads should be released

[d4ilyrun]

Reference

POSIX - exec()

A call to any exec function from a process with more than one thread shall result in all threads being terminated

Link

[d4ilyrun]

Note to self: we should be careful not to kill a process that is currently holding a lock somewhere in kernel land.
This not only applies to this specific location, but also when killing a thread through a regular call to exit.

We currently kill a thread right before rescheduling it, but what if it had acquired a lock prior to being switched out?