pkg_hash: don't swallow dependencies

pkg_hash: don't swallow dependencies

Checking for unsatisfiable dependencies had the unwanted side-effect of
making opkg skip **all** dependencies. Fix that by clearing the
dependencies_checked flag after calling to
pkg_hash_fetch_unsatisfied_dependencies(), similar to how it is also
done in opkg.c.

Fixes: 8769c75 ("pkg_hash: don't suggest incompatible packages")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>