Remove the unused +mkdep/+make-deps/s-proto.S/s-proto-cancel.S

Since

commit d73f5331
Author: Roland McGrath <roland@gnu.org>
Date:   Fri May 2 02:20:45 2003 +0000

    2003-05-01  Roland McGrath  <roland@redhat.com>

dependency is generated by passing -MD -MF to compiler.  Remove the unused
+mkdep, +make-deps, s-proto.S and s-proto-cancel.S.

This fixes BZ #28554.