complibs/libelf: use target ranlib

For portability, the right ranlib for the target must be passed to
libelf's configure.

Signed-off-by: "Titus von Boxberg" <titus@v9g.de>
(transplanted from e4a6fefcb0f5ecbcade3ae5edbe609560843aed1)

reporter_name="Thomas Petazzoni"

reporter_url="http://www.free-electrons.com/"

reporter_comment="Very basic testing only"