object: rename function 'typename' to 'type_name'

Rename C++ keyword in order to bring the codebase closer to being able
to be compiled with a C++ compiler.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/tag.c b/tag.c
index fcbe012..66210fd 100644
--- a/tag.c
+++ b/tag.c
@@ -47,7 +47,7 @@ int gpg_verify_tag(const struct object_id *oid, const char *name_to_report,
 				name_to_report ?
 				name_to_report :
 				find_unique_abbrev(oid->hash, DEFAULT_ABBREV),
-				typename(type));
+				type_name(type));
 
 	buf = read_sha1_file(oid->hash, &type, &size);
 	if (!buf)