hush: make SIGINT handling visually less confusing

hush: make SIGINT handling visually less confusing

$ echo $$
18448
$ echo $? <wait here, run "kill -INT 18448" in other shell><press enter>
   <=== NOTHING??
$

That empty line does not look right. After this patch:

$ echo $$
18448
$ echo $? <wait here, run "kill -INT 18448" in other shell><press enter>
^C
$

function                                             old     new   delta
fgetc_interactive                                    245     246      +1

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>