[gnome-calendar] source-dialog: make NULL comparison explicit

[Erick Pérez Castellanos <erickpc src gnome org>]

commit 53e3c04bb2967e9fccfb96105cc553ad77e047f7
Author: Erick Pérez Castellanos <erick red gmail com>
Date:   Sat May 16 18:12:50 2015 -0400

    source-dialog: make NULL comparison explicit

 src/gcal-source-dialog.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/gcal-source-dialog.c b/src/gcal-source-dialog.c
index b6038f2..9461b28 100644
--- a/src/gcal-source-dialog.c
+++ b/src/gcal-source-dialog.c
@@ -1394,10 +1394,10 @@ prompt_credentials (GcalSourceDialog  *dialog,
 
   if (response == GTK_RESPONSE_OK)
     {
-      if (username)
+      if (username != NULL)
         *username = g_strdup (gtk_entry_get_text (GTK_ENTRY (priv->credentials_user_entry)));
 
-      if (password)
+      if (password != NULL)
         *password = g_strdup (gtk_entry_get_text (GTK_ENTRY (priv->credentials_password_entry)));
     }