Mark tags to bazel targets

[hcoona]

Is your feature request related to a problem?

The project could build with GCC4.8 + CMake but failed to build with GCC4.8+Bazel. I cannot understand it although I know the higher version of GRPC could not compile with GCC4.8.

I think most of the core components rely on nothing than some extremely basic libraries such as abseil, gsl, gtest & google benchmark. We at least should support bazel build for these targets.

Describe the solution you'd like

I'd like to mark the bazel targets with tags, so we can easily to exclude some components. For example, excluding OTLP would significantly simplify dependencies.

** Example **

cc_test(
    name = "otlp_recordable_test",
    srcs = ["test/otlp_recordable_test.cc"],
    deps = [
        ":otlp_recordable",
        "@com_google_googletest//:gtest_main",
    ],
    tags = ["otlp"],
)

bazel build //... --build_tag_filters=-otlp

[lalitb]

Thanks for bringing this up.

Bazel build for GCC4.8 was disabled in this PR once grpc and bazel version was upgraded. As you rightly mentioned higher version of gRPC doesn't compile with gcc4.8.

For CMake, we use the latest gRPC version for > gcc5.1 and older compatible gRPC version for gcc4.8 as done in this PR

Though I am not a bazel expert ( and we are missing expertise for that in the forum ), your approach for being able to choose/exclude the bazel target based on the platform looks a good approach.