Race condition -- Hugs 1.4

[Friedhelm Wrensch]

Hi,

I believe there is a nasty race condition in Hugs 1.4:

If the user enters the quit command :q, then presses the Interrupt key
fast enough and quits again, Hugs may crash.

This is because the target of catch_error is local to interpret,
which is out of scope after quitting.

Proposed fix for hugs.c:

            case QUIT   : breakOn(FALSE);   /* disable break trapping */
                          return;           /* before returning */

Friedhelm