opkg: update to latest Git head

opkg: update to latest Git head

This update fixes some cosmetical issues and a number of segmentation
faults when parsing lists having Conflicts or Replaces tags.

d217daf libopkg: fix replacelist parsing and writing
9dd9a07 libopkg: fix segmentation fault when traversing conflicts
34571ba libopkg: consider provided packages in pkg_vec_mark_if_matches()
18740e6 opkg_download: print error when fork() fails
e3d7330 libopkg: don't print unresolved dependencies twice

Signed-off-by: Jo-Philipp Wich <jo@mein.io>