Merge branch 'jc/diff-algo-attribute'

The "diff" drivers specified by the "diff" attribute attached to
paths can now specify which algorithm (e.g. histogram) to use.

* jc/diff-algo-attribute:
  diff: teach diff to read algorithm from diff driver
  diff: consolidate diff algorithm option parsing

diff.h

@@ -333,6 +333,7 @@ struct diff_options {
 	int prefix_length;
 	const char *stat_sep;
 	int xdl_opts;
+	int ignore_driver_algorithm;
 
 	/* see Documentation/diff-options.txt */
 	char **anchors;