Provide a ruby native gem for aarch64 linux

[jtattermusch]

protobuf ruby builds fine on aarch64 linux (arm64) and the tests are passing there.
The missing piece is that we currently don't provide pre-built package (=native gem) for aarch64 linux.

Related issue:
grpc/grpc#26391

[jtattermusch]

Ruby artifacts build happens here: https://github.com/protocolbuffers/protobuf/blob/master/kokoro/release/ruby/linux/ruby/ruby_build.sh

protobuf/ruby/Rakefile

Line 96 in 0b8d13a

ext.cross_platform = [

[jtattermusch]

FTR linux-aarch64 support has been added to rake-compiler-dock in rake-compiler/rake-compiler-dock#54

[JasonLunn]

Closing this because in version 3.22 protobuf is planning to experiment with releasing only a source gem.

If this experiment is unsuccessful and we revert to building binary gems for some platforms, we'll evaluate whether it makes sense to add aarch64 linux at that time.

CC: @deannagarcia @haberman

[chadlwilson]

@JasonLunn Was this experiment successful? I am inferring perhaps not, since 3.22 still seems to have binary gems included?

I opened #12144 but now realise it's a possible duplicate of this. Would there be an intention to re-open this?

[deannagarcia]

We had enough requests for binary gems that we decided to keep them. We are currently working on adding an aarch64 linux binary, and we expect it to be in a patch release for v22.