process: Add debug wrappers for pthread mutex operations

process: Add debug wrappers for pthread mutex operations

This is the beginning of the work to convert the concurrency model
from fork-bomb based model to pthreads.

To get started, add a wrapper functions to handle locking. Namely,
these wrappers will log where the lock was acquired and will print out
who is holding it in case of contention.

Signed-off-by: Timo Kokkonen <timo.t.kokkonen@iki.fi>