Use zip_XXX_t instead of struct zip_XXX or enum zip_XXX.

lib/zip_get_archive_comment.c

diff --git a/lib/zip_get_archive_comment.c b/lib/zip_get_archive_comment.c
index 971883f..78f8ca0 100644
--- a/lib/zip_get_archive_comment.c
+++ b/lib/zip_get_archive_comment.c
@@ -38,9 +38,9 @@
 
 
 ZIP_EXTERN const char *
-zip_get_archive_comment(struct zip *za, int *lenp, zip_flags_t flags)
+zip_get_archive_comment(zip_t *za, int *lenp, zip_flags_t flags)
 {
-    struct zip_string *comment;
+    zip_string_t *comment;
     zip_uint32_t len;
     const zip_uint8_t *str;