Some host fail on `assert (!"foo")', which expands to

((!"foo") ? (void)0 : __assert("!"foo."", __FILE__, __LINE__))
Reported by Nelson Beebee.
* src/output.c, src/vcg.c: Replace `assert (!"it succeeded")' with
`#define it_succeeded 0' and `assert (it_succeeded)'.

THANKS

@@ -19,6 +19,7 @@ Keith Browne            kbrowne@legato.com
 Laurent Mascherpa       laurent.mascherpa@epita.fr
 Marc Autret             autret_m@epita.fr
 Neil Booth              NeilB@earthling.net
+Nelson H. F. Beebe      beebe@math.utah.edu
 Noah Friedman           friedman@gnu.org
 Pascal Bart             pascal.bart@epita.fr
 Paul Eggert             eggert@twinsun.com