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            [email protected]
 Laurent Mascherpa       [email protected]
 Marc Autret             [email protected]
 Neil Booth              [email protected]
+Nelson H. F. Beebe      [email protected]
 Noah Friedman           [email protected]
 Pascal Bart             [email protected]
 Paul Eggert             [email protected]