ncsid: Fix interruptible RA

Capturing directly from a subshell into a variable blocks the bash
process from waiting on a signal. Instead, use `coproc` and `read` to
achieve the same result.

Change-Id: I7ad8b01e2508c5a0c871d77d3a629ac5812656c5
Signed-off-by: William A. Kennington III <wak@google.com>
2 files changed