Fix DNS reply parsing loop and stall

When the record type was unknown and uxSourceBytesRemaining was less
than sizeof(DNSAnswerRecord_t), the else branch consumed no bytes,
causing the parser to loop indefinitely. Add a break for that case.

Also add an ANCOUNT sanity check that rejects packets claiming more
answer records than the remaining buffer can physically contain, and
guard AAAA record handling with ipconfigUSE_IPv6.

Author: AniruddhaKanhere

.github/.cSpellWords.txt

@@ -17,6 +17,7 @@ ALLNS
 Allo
 ALMUL
 AMBA
+ANCOUNT
 amsdu
 ANAR
 ANARBMCR