Allow shared zlib-ng

[Mystro256]

Should be self explanatory.

Allows for using shared zlib-ng if found by pkgconfig, similar to how zstd works.

[delroth]

@dolphin-emu-bot rebuild

[Mystro256]

I guess I should also add "check_vendoring_approved(zlib-ng)"? I'm not sure how this logic works, so I didn't touch it.

[delroth]

Please do -- I started working on this to make it easier for package maintainers to notice when we add new dependencies, by having an allowlist of things that they are ok with us vendoring. The idea being that when bumping to the next package version any new vendored dependency that you haven't explicitly approved (by adding it to an allowlist in a cmake configuration flag) would cause the build to fail, instead of silently using a vendored version of the lib.

Do you maintain the Fedora package for Dolphin? If so I'd love feedback on whether that's useful / how to make it more useful :)

(It wasn't there for zlib-ng because we didn't support non-vendored.)

[delroth]

(https://github.com/dolphin-emu/dolphin/blob/master/CMake/CheckVendoringApproved.cmake has documentation)

[Mystro256]

Thanks! I noticed there's a linking error:
/usr/bin/ld: ../DiscIO/libdiscio.a(CompressedBlob.cpp.o): undefined reference to symbol 'inflateEnd'

So I guess I should have waited for the build to complete before pushing. I believe inflateEnd comes from zlib if I recall correctly.

[Mystro256]

Hmm having trouble with this one... It keeps trying to link against the system libz instead of libz-ng, causing missing symbol issues.

[Mystro256]

Sorry for the delay. I rebased on the latest master and it looks like dolphin_find_optional_system_library_pkgconfig resolves all my issues.

[Mystro256]

@TellowKrinkle thanks for implementing this. It makes everything easier :)

[AdmiralCurtiss]

@TellowKrinkle I assume this is fine? Do you know if we need any specific zlib-ng version?

[TellowKrinkle]

Yes, I think this is fine. I do not know any specific zlib-ng version, and while we could try to search through to figure out, I'd be in favor of the "put it in with no minimum, and add a minimum if we get an issue about it failing to compile" solution

[AdmiralCurtiss]

Reasonable.

[SuperSamus]

Thanks! I noticed there's a linking error:
/usr/bin/ld: ../DiscIO/libdiscio.a(CompressedBlob.cpp.o): undefined reference to symbol 'inflateEnd'

I found out that it also happens if zlib-ng is shared, but minizip-ng is Dolphin's.
(Guess I should link #12070)