rev-list: add an option to mark fewer edges as uninteresting

In commit fbd4a70 (list-objects: mark more commits as edges in
mark_edges_uninteresting - 2013-08-16), we marked an increasing number
of edges uninteresting.  This change, and the subsequent change to make
this conditional on --objects-edge, are used by --thin to make much
smaller packs for shallow clones.

Unfortunately, they cause a significant performance regression when
pushing non-shallow clones with lots of refs (23.322 seconds vs.
4.785 seconds with 22400 refs).  Add an option to git rev-list,
--objects-edge-aggressive, that preserves this more aggressive behavior,
while leaving --objects-edge to provide more performant behavior.
Preserve the current behavior for the moment by using the aggressive
option.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/revision.h b/revision.h
index 9cb5adc..033a244 100644
--- a/revision.h
+++ b/revision.h
@@ -93,6 +93,7 @@
 			blob_objects:1,
 			verify_objects:1,
 			edge_hint:1,
+			edge_hint_aggressive:1,
 			limited:1,
 			unpacked:1,
 			boundary:2,