feat(ffi): add http1_allow_multiline_headers

[deantvv]

Close issue #2885

[seanmonstar]

Thanks for the PR! <3

Looks like the function names are out of sync. The hyper_clientconn_options_http1_allow_multiline_headers name seems preferable to me, since it is an HTTP/1 specific option. I think just running the gen_header.sh script should fix it up for you.

[deantvv]

Fixed in new commit.

[seanmonstar]

Thanks :D

[seanmonstar]

Would you want to add the usage in curl? If not, I can a little later, but just checking first.

[deantvv]

I can try that in this weekend, but it would probably need some time for me to understand some curl source code stuff.
Is there any guidance or documentation that I can refer to when I try to do this?
Thanks in advance.

[seanmonstar]

I tried to add it yesterday, and noticed that curl expects the format of multiline headers to be a little different than hyper treats them, so it'll be more work than expected. I'll need to file an issue on the curl repo.