verify_signed_buffer: prefer close_tempfile() to close()

We do a manual close() on the descriptor provided to us by
mks_tempfile. But this runs contrary to the advice in
tempfile.h, which notes that you should always use
close_tempfile(). Otherwise the descriptor may be reused
without the tempfile object knowing it, and the later call
to delete_tempfile() could close a random descriptor.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gpg-interface.c

@@ -215,7 +215,7 @@ int verify_signed_buffer(const char *payload, size_t payload_size,
 		delete_tempfile(&temp);
 		return -1;
 	}
-	close(fd);
+	close_tempfile(&temp);
 
 	argv_array_pushl(&gpg.args,
 			 gpg_program,