Update libsdp to the latest 1.1.108-0.17.ga6958ef.

The only relevant change here is the support for IPv6 in the config
file. The previous version of this supported IPv6 but not in the
config. The change for that ended up removing __sdp_sockaddr_to_sdp
which the IPV4 config code required; the IPv6 fix resolved the lack of
that symbol.

Note that the ChangeLog was lacking entries for which we already had the
changes for, which itself was an upstream bug.

Obtained from: https://www.openfabrics.org/downloads/libsdp/libsdp-1.1.108-0.17.ga6958ef.tar.gz
Sponsored by: EMC / Isilon Storage Division