Fix , in long TXT data

[Fneufneu]

I use amphp/dns which rely on libdns and i discovered that all my DKIM TXT queries wasn't valid.
I found some "," in all response.

For exemple with google dkim: TXT of 20230601._domainkey.gmail.com

libdns give me: (import part is 4T4HZb2,PY2bQtE)

string(411) "v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAntvSKT1hkqhKe0xcaZ0x+QbouDsJuBfby/S82jxsoC/SodmfmVs2D1KAH3mi1AqdMdU12h2VfETeOJkgGYq5ljd996AJ7ud2SyOLQmlhaNHH7Lx+Mdab8/zDN1SdxPARDgcM7AsRECHwQ15R20FaKUABGu4NTbR2fDKnYwiq5jQyBkLWP+LgGOgfUF4T4HZb2,PY2bQtEP6QeqOtcW4rrsH24L7XhD+HSZb1hsitrE0VPbhJzxDwI4JF815XMnSVjZgYUXP8CxI1Y0FONlqtQYgsorZ9apoW1KPQe8brSSlRsi9sXB/tu56LmG7tEDNmrZ5XUwQYUUADBOu7t1niwXwIDAQAB"

and nslookup -type=txt 20230601._domainkey.gmail.com: (important part is 4T4HZb2" "PY2bQtE)

20230601._domainkey.gmail.com   text = "v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAntvSKT1hkqhKe0xcaZ0x+QbouDsJuBfby/S82jxsoC/SodmfmVs2D1KAH3mi1AqdMdU12h2VfETeOJkgGYq5ljd996AJ7ud2SyOLQmlhaNHH7Lx+Mdab8/zDN1SdxPARDgcM7AsRECHwQ15R20FaKUABGu4NTbR2fDKnYwiq5jQyBkLWP+LgGOgfUF4T4HZb2" "PY2bQtEP6QeqOtcW4rrsH24L7XhD+HSZb1hsitrE0VPbhJzxDwI4JF815XMnSVjZgYUXP8CxI1Y0FONlqtQYgsorZ9apoW1KPQe8brSSlRsi9sXB/tu56LmG7tEDNmrZ5XUwQYUUADBOu7t1niwXwIDAQAB"

libdns obviously implode both data field with a , which give a wrong answer.

So this small PR fixe the issue but i don't know if it's brakes something else or a proper fix for master branch.

[kelunik]

We likely can't change the behavior there for everything? Have you done some research in the relevant specs?