Content-Length not checked by http protocol

[hostilefork]

The http protocol does not honor the Content-Length header field, and instead reads data as much data as a socket provides. This was discovered when the httpd.reb server was using length of a string in codepoints for the Content-Length, instead of the length of the binary encoded UTF-8.

So for instance, the header claimed a content length of 19 when serving the string HighCodepointCat(😺), which is actually 22 bytes in size. However the HTTP read received the full 22 bytes:

>> data: read http://127.0.0.1:8000 
== #{48696768436F6465706F696E7443617428F09F98BA29}

>> length? data
== 22