Remove unused member in struct object_context

The tree member of struct object_context is unused except in one place
where we write to it.  Since there are no users of this member, remove
it.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -1306,7 +1306,6 @@ static inline int hex2chr(const char *s)
 #define FALLBACK_DEFAULT_ABBREV 7
 
 struct object_context {
-	unsigned char tree[20];
 	unsigned mode;
 	/*
 	 * symlink_path is only used by get_tree_entry_follow_symlinks,

sha1_name.c

@@ -1698,7 +1698,6 @@ static int get_oid_with_context_1(const char *name,
 								   name, len);
 				}
 			}
-			hashcpy(oc->tree, tree_oid.hash);
 			if (flags & GET_OID_RECORD_PATH)
 				oc->path = xstrdup(filename);