[PATCH] HTTP: include SSI header only where it's needed

[Piotr Sikora]

Hey Maxim,

> I don't think this change is needed.  Current approach is in line
> with what's done for other headers, and I see no serious enough
> reasons to change things.

Except that other headers (i.e. cache, ssl, v2) need to be included in
"core" http, because the functions they expose are used in "core"
http, whereas SSI is not. Basically, cache, ssl & v2 are all
compile-time options of the "core" http, whereas SSI is just an http
module and pulling SSI header in "core" http breaks layering &
separation of the modules.

This doesn't really matter if you compile nginx as a big monolith, but
if you want to go DSO route or build modules separately from "core"
http, then "core" http (i.e. ngx_http.h) shouldn't be pulling headers
from non-"core" http modules.

Best regards,
Piotr Sikora