Buffer: check realloc return value.
OCI: check for realloc return value.
DNS_rr: replace ttl with signed integer (rfc1035).
DNSQuery: create new function to set record header.

* Set destructor to virtual.
* Set _rr_ans, _rr_aut, and _rr_add to NULL after destruction.
Socket: initialize socket address length.
libvos: set pointer to NULL after freed.