:TRQ-2663  Instability in 4.2.8

This fixes a problem in the mutex_mgr where the default
is_locked value of false would always invalidate the mutex
and make it not work. No locking would occur.

Conflicts:

	src/lib/Libnet/net_common.c

Conflicts:

	src/lib/Libutils/u_mutex_mgr.cpp