- enable concurrency according to environment variable PTHREAD_CONCURRENCY
- add idle VP wakeup if there are additional jobs and idle VPs
- make reidlequeue per VP
- enable spinning for locks
- fix race condition in alarm processing
- fix race condition in mutex locking
- make debugging output line buffered and add VP prefix to debug lines
- add PTHREAD_PID_DEBUG which prints the pid before each debuglog line
- output thread returned in pthread__next
- add asserts in pthread__sched akin to asserts in pthread__sched_bulk:
check if scheduled thread is at front/end of queue
- pthread__upcall: output event/interrupted LWP count instead of LWPid
of the first event/interrupted LWP (since unblock upcalls can have
multiple event LWPs).
- pthread__find_interrupted: output LWPid here