Fix bugs with memory allocation in ego.

Fix bugs with memory allocation in ego.

cf/cf_loop.c and share/put.c tried to read the next pointer in an
element of a linked list after freeing the element.  ud/ud_copy.c
tried to read beyond the end of the _defs_ array: it only has
_nrexpldefs_ elements, not _nrdefs_ elements.

These bugs caused core dumps on OpenBSD.  Its malloc() put _defs_ near
the end of a page, so reading beyond the end crossed into an unmapped
page.  Its free() wrote junk bytes and changed the next pointer to
0xdfdfdfdfdfdfdfdf.