opkg: update to latest Git head

opkg: update to latest Git head

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
3b417b9 opkg_download: decode file:/ URLs
71c27cb file_util: implement urldecode_path()
d1fe095 file_util: consolidate hex/unhex routines
ebdfc12 add opkg option http_timeout
9f003e3 opkg: encode archive filenames while constructing download URLs
73e6c81 file_util: implement urlencode_path() helper
468158f libopkg: fix SHA256 calculation for big endian system
4bd8601 pkg_parse: fix segfault when parsing descriptions with leading newlines
52fc006 pkg_alternatives: pass if the desired symlink already exists
c668fce opkg: add --no-check-certificate argument
04e279e pkg_alternatives: use ERROR level for symlink failure
546bc72 pkg: alternatives support

Signed-off-by: Jo-Philipp Wich <jo@mein.io>
(backported from commit 1bd18f2b5cbf1c9c384e9725eff7804decf88c90)