diff: --full-index

A new option, --full-index, is introduced to diff family.  This
causes the full object name of pre- and post-images to appear on
the index line of patch formatted output, to be used in
conjunction with --allow-binary-replacement option of git-apply.

Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/diff.h b/diff.h
index 1259079..9b2e1e6 100644
--- a/diff.h
+++ b/diff.h
@@ -32,7 +32,8 @@
 	const char *orderfile;
 	const char *pickaxe;
 	unsigned recursive:1,
-		 tree_in_recursive:1;
+		 tree_in_recursive:1,
+		 full_index:1;
 	int break_opt;
 	int detect_rename;
 	int find_copies_harder;
@@ -96,6 +97,7 @@
 "  -u            synonym for -p.\n" \
 "  --name-only   show only names of changed files.\n" \
 "  --name-status show names and status of changed files.\n" \
+"  --full-index  show full object name on index ines.\n" \
 "  -R            swap input file pairs.\n" \
 "  -B            detect complete rewrites.\n" \
 "  -M            detect renames.\n" \