CVE-2026-81634: bounds-check the scratch buffer in rrset_canonical() and
rrset_canonicalize_to_buffer() before writing the RRSIG rdata, the first
canonical owner name and each RR's rdata, so a large rrset can no longer
be written past the end of the buffer
CVE-2026-80225: cap the number of pipelined TCP/DoT queries drained per
event-loop visit in tcp_req_info_read_again() and tcp_more_read_again()
and defer the remainder via a zero-delay timer, so one connection can no
longer starve the other file descriptors