This patch fixes adventure(6) to use `extern' on declarations of

This patch fixes adventure(6) to use `extern' on declarations of
objects in its header file, and to add corresponding definitions to
init.c accordingly.  (See the C standard - relying on linker commons
where there are multiple uninitialised declarations of an object in
the program traditionally works on Unix, but is not standard C.)

The patch also removes a bit-rotten code fragment under #ifdef
OLDSTUFF.

Patch submitted in PR 8105 by Joseph Myers <jsm28@cam.ac.uk>