sulogin: remove alarm handling, as it is redundant there.
code shrink. After all differences cancel out:
text data bss dec hex filename
777543 1000 9532 788075 c066b busybox_old
777543 1000 9532 788075 c066b busybox_unstripped
* do not make backup copy by copying (just retain old file)
* correctly fall back to /etc/passwd if user is not in shadow
* fix bug with overlong passwd entries
* be permissive on some kinds of failures
* reduce stack usage
* code size: -500 bytes