POSIX states that creation of a mutex with default attributes
is unspecified whether the mutex is recursive or non-recursive.
We specifically want non-recursive (deadlock is desirable in
flushing out coding bugs that used our mutex incorrectly).
* src/util/threads-pthread.c (virMutexInit): Specifically request
non-recursive mutex, rather than relying on unspecified default.
* src/util/threads-pthread.c: pthreads APIs do not set errno, instead
the return value is the positive errno. Set errno based on the return
value in the wrappers
