Unlock minherit(2)

Unlock minherit(2)

struct uvm_map's .addr is protected by the map's lock and .{min,max}_offset
are immutable.

uvm_map_inherit() locks the VM map upon entry, sets the desired inheritance
mode for the given address range (validated outside the lock) and unlocks
the map itself.

fork(2), i.e. uvm_mapent_forkcopy(), first locks both old and new maps and
then copies entries over as per the inheritance type.

futex(2), another user of struct vm_map_entry's .inheritance member, also
locks the map accordingly.

OK mpi