scripts: use generic urls for sourceforge

For expat, duma, and strace, use the generic url and 302 to the mirror
instead of trying to download a file from a downed mirror and
failing.

Signed-off-by: Bryan Hundven <bryanhundven@gmail.com>
Message-Id: <b69ebeb72fef93c04c84.1345364051@flambe.is-a-geek.org>

 #!/bin/sh

 call_to=@@DEFAULT_LD@@

 case "${CTNG_LD_IS}" in

     bfd)    call_to=bfd;;

     gold)   call_to=gold;;

 esac

 exec "${0}.${call_to}" "$@"

 exit $?