Now that h1 and legacy HTTP are two distinct things, there's no need
to keep the legacy HTTP parsers in h1.c since they're only used by
the legacy code in proto_http.c, and h1.h doesn't need to include
hdr_idx anymore. This concerns the following functions :
- http_parse_reqline();
- http_parse_stsline();
- http_msg_analyzer();
- http_forward_trailers();
All of these were moved to http_msg.c.
Lots of HTTP code still uses struct http_msg. Not only this code is
still huge, but it's part of the legacy interface. Let's move most
of these functions to a separate file http_msg.c to make it more
visible which file relies on what. It's mostly symmetrical with
what is present in http_htx.c.
The function http_transform_header_str() which used to rely on two
function pointers to look up a header was simplified to rely on
two variants http_legacy_replace_{,full_}header(), making both
sides of the function much simpler.
No code was changed beyond these moves.
