virsh-domain: Avoid killing ssh transport tunnels when cancelling job

virsh-domain: Avoid killing ssh transport tunnels when cancelling job

The vshWatchJob function registers a SIGINT handler that is used to
abort the active job and does not terminate virsh. Unfortunately, this
breaks when using the ssh transport as SIGINT is sent to the foreground
process group including the ssh transport processes which terminate.
This breaks the connection and migration is left in a insane state.

With this patch the terminal is modified to ignore key binding that
sends SIGINT and does the handling manually.

Resoves: https://bugzilla.redhat.com/show_bug.cgi?id=983348