gnome-keyring does not discard stored secrets in some cases

[Florian Weimer <fw () deneb enyo de>]

We've received a bug report that gnome-keyring client library does not
instruct the daemon to discard secrets when using the
gnome_keyring_lock_all_sync function:

<http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=697896>
<https://bugzilla.gnome.org/show_bug.cgi?id=690466>

The function is simply not implemented.

I had trouble finding a caller of this function, but the submitter
indicated that gnome-power-manager uses it in older versions:

<http://git.gnome.org/browse/gnome-power-manager/tree/src/gpm-control.c?h=gnome-2-32#n162>

I'm not sure if this needs a CVE, but it's probably worth fixing
anyway.