Support proxy-protocol-v2 crc32c tlv.
Support proxy-protocol-v2 crc32c tlv.

Compute checksum if crc32c tlv is send in proxy-protocol-v2 header.

gquintard/Varnish-Cache,gquintard/Varnish-Cache,gquintard/Varnish-Cache,gquintard/Varnish-Cache