[BusyBox] dc applet shouldn't print result by default

[Paul Whittaker]

In Busybox 1.0.0pre10 and CVS, the dc applet's behaviour isn't 
compatible with GNU dc, in that the former prints a result by default 
and the latter doesn't.  As a trivial example, compare the output of:

     echo "1 1 +" | dc

... from Busybox and GNU versions of dc. Disabling the invocation of 
print() in stack_machine() (miscutils/dc.c:159) seems to have the 
desired effect.

This difference wouldn't be a major concern were it not for the fact 
that I am trying to write a shell script that will work both in and out 
  of a busybox environment.