Net-SNMP 5.9.4 leaks memory

[cmb69]

Net-SNMP 5.9.4 doesn't free the tclist data structure (a couple of KB). That results in a harmless but annoying memory leak for PHP, because the leaking memory is allocated during ext/snmp module initialization; that means whenever you run a PHP process under a leak detector with ext/snmp loaded, you get a leak report.

I've submitted net-snmp/net-snmp#891; let's see where that goes.