Change mechanism used to open files and sockets, so that interrupts

Change mechanism used to open files and sockets, so that interrupts
are enabled during the open.  This is necessary, because any
network-based operation could potentially hang for long periods of
time, and it's desirable for the user to be able to interrupt out of
the operation.

This change requires microcode version 11.154 (or the corresponding
version 13).

In addition to this change, the low-level channel code was changed to
eliminate the now-obsolete gc-daemon interlocking code.