Add a proto_lang_toolchain for javalite

[rafi-kamal]

So that javalite can be used from Bazel. Related discussion: #6867

[rafi-kamal]

@ejona86 do you know how can I test it? Is there a java_lite_proto_library defined somewhere that can depend on this rule?

[ejona86]

It looks like your examples include a java_lite_proto_library :)

protobuf/examples/BUILD

Lines 73 to 76 in 4e93585

	java_lite_proto_library(
	name = "addressbook_java_lite_proto",
	deps = [":addressbook_proto"],
	)

(And I only know this because of the build failure you mentioned in #6898)

That means you should also update it's workspace to use a local_repository (just like com_google_protobuf) instead of the http_archive:

protobuf/examples/WORKSPACE

Lines 24 to 28 in 4e93585

	http_archive(
	name = "com_google_protobuf_javalite",
	strip_prefix = "protobuf-javalite",
	urls = ["https://github.com/protocolbuffers/protobuf/archive/javalite.zip"],
	)

[ejona86]

I fixed a bug and updated the examples, but now it is running for me. You can test by cd examples/; bazel build :addressbook_java_lite_proto

[rafi-kamal]

Thank you very much :)