Add missing zip_close in error case (found by Coverity; CID 733097).

Also, thank Coverity for offering free scans.

THANKS

diff --git a/THANKS b/THANKS
index 4b66477..7485f16 100644
--- a/THANKS
+++ b/THANKS
@@ -6,6 +6,7 @@
 Alexander Galanin <al@galanin.nnov.ru>
 Alexandr Shadchin <alexandr.shadchin@gmail.com>
 Andrew Brampton <brampton@gmail.com>
+Coverity <info@coverity.com>
 Del Merritt <del@alum.mit.edu>
 François Simon <AT.GFI.Francois.SIMON@sesam-vitale.fr>
 Heiko Hund <heiko@ist.eigentlich.net>