[core] remove obsolete comment about r->gw_dechunk
[core] remove obsolete comment about r->gw_dechunk

r->gw_dechunk->b is not a candidate for using generic chunk buffers.
chunked headers are generally smaller and fit in default 64 byte alloc.
Also, lighttpd limits chunked header to 1k.

Avoid unneeded optimization since HTTP/1.1 use is likely to diminish
over time in favor of HTTP/2 or HTTP/3 or later.

gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,lighttpd/lighttpd1.4,lighttpd/lighttpd1.4