Add some files

1) ld.elf_so, so that we don't need out-of-place copies of
   a few headers (decreases diffs to NetBSD master)
2) enough files so that our hierarchy gets recognized as NETBSDSRCDIR
   (so that the files added in step "1" are found during the build process)
Merge branch 'netbsd-cvs'
Remove no longer necessary copies.