nss_db: protect against empty mappings

[Andreas Schwab]

On Jun 18 2019, DJ Delorie <dj@redhat.com> wrote:

>> Where is this variable used?
>
> It's not, it's just there to make sure the call to is_selinux_enabled
> really happens.

If calling is_selinux_enabled has side effects then it cannot be elided.
If it doesn't, then it is pointless.  Assignment to a write-only
variable doesn't change that.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
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