Fix directory navigation in Dolphin::Terminal.

When navigating in Dolphin it attempts to keep any open Terminal (F4)
in sync by changing the directory in the shell. It does this by
sending a "^C; cd $DIRECTORY" however shells under FreeBSD treat "^C"
as a literal string and not SIGINT. Fix this by sending SIGINT to the
shell instead of "^C".

It appears Linux does not exhibit this behaviour.

Patch originally written by David Naylor, from the KDE-FreeBSD team.



(cherry picked from commit 5f78219e18073e475ed1f1865a1a2be1fafd60cf)