Re-enable optimiser in 2001/williams

The bugs.md was updated to remind people when debugging crashes that it
would be wise to have -O0 and -g (or if they can -ggdb3). That should be
noted in general for debugging but it's especially useful for crashes
and I'm trying to get this part done so I can resume 2019.

2001/williams/Makefile

@@ -68,7 +68,7 @@ CINCLUDE= -I ${X11_INCDIR} -I ${X11_INCDIR}/X11
 
 # Optimization
 #
-OPT= -ggdb3
+OPT= -O3
 
 # Default flags for ANSI C compilation
 #