[Toybox] Toybox bc run away interactive process

[Sasha Toltec]

When attempting to use ctrl-c to kill the toybox bc implementation
while in non-interactive mode a bug results in it entering interactive
mode while the program continues to run and then the user loses
control of both interactive and non-interactive modes.

To reproduce:
echo "s(131231)" | ./bc -l   .. and hit ctrl-c

This consumes many GB of memory before finally exhausting the system.


Sasha Toltec
Toltec Enterprises
sashatoltec1 at gmail.com