virclosecallbacks: Remove old close callbacks code

virclosecallbacks: Remove old close callbacks code

Now that all code was refactored to use the new version we can remove
the old code.

For now the new close callbacks code has no error messages so
syntax-check forced me to remove the POTFILES entry for
virclosecallbacks.c

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>