cli: Guard deprecated g_type_init calls

g_type_init was deprecated in GLib 2.35.1.  In order to compile
cleanly, guard these with a suitable #if.

(commit msg from https://bugs.freedesktop.org/attachment.cgi?id=73774 )

lib/database.cc

@@ -649,7 +649,9 @@ notmuch_database_open (const char *path,
     }
 
     /* Initialize the GLib type system and threads */
+#if !GLIB_CHECK_VERSION(2, 35, 1)
     g_type_init ();
+#endif
 
     /* Initialize gmime */
     if (! initialized) {

notmuch.c

@@ -291,7 +291,9 @@ main (int argc, char *argv[])
     local = talloc_new (NULL);
 
     g_mime_init (0);
+#if !GLIB_CHECK_VERSION(2, 35, 1)
     g_type_init ();
+#endif
 
     /* Globally default to the current output format version. */
     notmuch_format_version = NOTMUCH_FORMAT_CUR;