Global #defines don't propagate in version compat.
Imported from http://bugzilla.roxen.com/bugzilla/show_bug.cgi?id=3507
Reported by @grubba
$ pike -DFOOBAR=GAZONK
Pike v7.5 release 12 running Hilfe v3.5 (Incremental Pike Frontend)
> FOOBAR;
Compiler Error: 1:Undefined identifier "GAZONK".
Terminal closed.
$ pike -DFOOBAR=GAZONK -V7.4
Pike v7.5 release 12 running Hilfe v3.5 (Incremental Pike Frontend)
> FOOBAR;
Compiler Error: 1:Undefined identifier "FOOBAR".
Terminal closed.