[filter/purge.c] try to get rid of compiler warning with GCC 4.5
[filter/purge.c] try to get rid of compiler warning with GCC 4.5

mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs