[RFA/testsuite] Fix failures in observer.exp

[Joel Brobecker]

> > +    # Call observer_notify_normal_stop. Note that this procedure
> > +    # takes one argument, but this argument is ignored by the observer
> > +    # callbacks we have installed. So we just pass an arbitrary value.
> > +    gdb_test "call observer_notify_normal_stop (0)" "" \
> 
> Full stops get two spaces.  Otherwise obviously OK.

Grrr, I can't believe I made this mistake! Fixed and checked in.

Thank you!
-- 
Joel