Remove get_object_hash.

Convert all instances of get_object_hash to use an appropriate reference
to the hash member of the oid member of struct object.  This provides no
functional change, as it is essentially a macro substitution.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Jeff King <peff@peff.net>
diff --git a/builtin/notes.c b/builtin/notes.c
index 1a67859..52aa9af 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -707,7 +707,7 @@
 		die("Could not parse commit from NOTES_MERGE_PARTIAL.");
 
 	if (partial->parents)
-		hashcpy(parent_sha1, get_object_hash(partial->parents->item->object));
+		hashcpy(parent_sha1, partial->parents->item->object.oid.hash);
 	else
 		hashclr(parent_sha1);