Enable `brotli` and `zstd`

[void-main-void]

For the windows builds on windows.php.net, would you please consider enabling brotli (br) and zstd for ext/curl? (To support these in the Accept-Encoding HTTP header.)

More and more web servers are supporting these algorithms and Chrome web browser also supports them. These algorithms generally have better compression ratio and may reduce amount of traffic when making curl requests with PHP.

Thanks in advance!

[cmb69]

This makes generally sense to me.

It's not quite clear how to handle this for PHP in practice, though. Sor far we have zstd as PECL dependency (used by external ext/zip, and maybe others), but no libbrotli builds. If we built against shared libraries, that would mean that we have two more DLLs to ship with PHP (and users may have to copy these; DLL hell, especially with Webserver modules like Apache). If we build against static libs, we may bloat php_curl.dll, and updates require to rebuild libcurl.

I should note that so far we're generally using static libraries for supported compression (zlib, bz2, lzma). For ext/curl we only support zlib.

I should also note that we're using the Makefile.vc shipped with libcurl, but that only supports zlib. We would need to switch to CMake builds (what may be a good idea anyway) to be able to with brotli and zstd support.

Maybe @nielsdos and @shivammathur have thoughts about this.

[cmb69]

Ah, just noticed that there is a brotli PECL extension; it looks like the Windows builds use libbrotli bundled by this extension.

[ndossche]

I'd be more in favor of the DLL approach because I think on the longer term this will be less overhead for us.

[cmb69]

We would need to switch to CMake builds (what may be a good idea anyway)

See curl/curl#15920.

PS: see winlibs/winlib-builder#40

[cmb69]

Brotli builder: winlibs/winlib-builder#38