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

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)'.