diff: drop `FILELIST_MATCH`

Now that non-pathspec matching diffs are implemented at the iterator
level, drop `FILELIST_MATCH`ing.

include/git2/diff.h

@@ -165,13 +165,6 @@ typedef enum {
 	/** Include unreadable files in the diff */
 	GIT_DIFF_INCLUDE_UNREADABLE_AS_UNTRACKED = (1u << 17),
 
-	/** Use literal path matching in the iterators.  This is more broad
-	*  than the DISABLE_PATHSPEC_MATCH flag.  The caller must provide an
-	*  array of paths (no patterns or prefixes).  Only values included in
-	*  that list will be returned.
-	*/
-	GIT_DIFF_ENABLE_FILELIST_MATCH = (1u << 18),
-
 	/*
 	 * Options controlling how output will be generated
 	 */

src/merge.c

@@ -2405,7 +2405,7 @@ static int merge_check_workdir(size_t *conflicts, git_repository *repo, git_inde
 	 * will be applied by the merge (including conflicts).  Ensure that there
 	 * are no changes in the workdir to these paths.
 	 */
-	opts.flags |= GIT_DIFF_ENABLE_FILELIST_MATCH;
+	opts.flags |= GIT_DIFF_DISABLE_PATHSPEC_MATCH;
 	opts.pathspec.count = merged_paths->length;
 	opts.pathspec.strings = (char **)merged_paths->contents;