Some diff refactorings to help code reuse

There are some diff functions that are useful in a rewritten
checkout and this lays some groundwork for that.  This contains
three main things:

1. Share the function diff uses to calculate the OID for a file
   in the working directory (now named `git_diff__oid_for_file`
2. Add a `git_diff__paired_foreach` function to iterator over
   two diff lists concurrently.  Convert status to use it.
3. Move all the string/prefix/index entry comparisons into
   function pointers inside the `git_diff_list` object so they
   can be switched between case sensitive and insensitive
   versions.  This makes them easier to reuse in various
   functions without replicating logic.  As part of this, move
   a couple of index functions out of diff.c and into index.c.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/iterator.c b/src/iterator.c
index 20878a060..33b775ce1 100644
--- a/src/iterator.c
+++ b/src/iterator.c
@@ -648,7 +648,7 @@ static int workdir_iterator__update_entry(workdir_iterator *wi)
 
 	wi->is_ignored = -1;
 
-	git_index__init_entry_from_stat(&ps->st, &wi->entry);
+	git_index_entry__init_from_stat(&wi->entry, &ps->st);
 
 	/* need different mode here to keep directories during iteration */
 	wi->entry.mode = git_futils_canonical_mode(ps->st.st_mode);