rcs blows up on suns

[Guy Harris]

> A minor point, but dereferencing zero only "works" on Vaxen that are
> running Berkeley Unix (don't know about USG).

Prior to the paging release of System V for the VAX (S5R2V2), S5 UNIX
suffered from the same problem as Berkeley UNIX - it allowed you to
reference location 0.  By default, it still does, but there is a linker
switch to build an executable image with no page 0.  John Bruner of Lawrence
Liverwurst Laboratory posted a set of kernel and linker changes to 4.2BSD
to make it support no-page-0 executables also.

	Guy Harris