[ostree] gpg-verifier: Fix compiler warning

[Colin Walters <walters src gnome org>]

commit ed9f5ce031cb0d28c2ea37c6e8ddf0300eb7f029
Author: Colin Walters <walters verbum org>
Date:   Fri Dec 4 09:51:14 2015 -0500

    gpg-verifier: Fix compiler warning

 src/libostree/ostree-gpg-verifier.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/libostree/ostree-gpg-verifier.c b/src/libostree/ostree-gpg-verifier.c
index eda69dc..b9a03a1 100644
--- a/src/libostree/ostree-gpg-verifier.c
+++ b/src/libostree/ostree-gpg-verifier.c
@@ -89,7 +89,7 @@ _ostree_gpg_verifier_check_signature (OstreeGpgVerifier  *self,
                                       GError            **error)
 {
   gpgme_ctx_t gpg_ctx = NULL;
-  gpgme_error_t gpg_error = NULL;
+  gpgme_error_t gpg_error = 0;
   gpgme_data_t data_buffer = NULL;
   gpgme_data_t signature_buffer = NULL;
   g_autofree char *tmp_dir = NULL;