delete a physical via
int delphvia(ptfig, ptvia)
Pointer to the figure in which the via should be deleted
Pointer to the via to be deleted.
delphvia delete the via pointed to by ptvia in the figure
pointed to by ptfig.
The list consistency is maintainded, and the space freed.
delphvia returns 1 if the via has been deleted, 0
if no such via exists in the list.
char *was_existing(ptfig, ptvia)
/* if only one exists, it's this one */
return delphvia(ptfig, ptvia) ? "you just killed it!"
: "wasn't here anyway";