Merge branch 'master' into uv_portability_fix

.github/CODEOWNERS

BUILD

CMakeLists.txt

Makefile

OWNERS

bazel/OWNERS

bazel/cc_grpc_library.bzl

bazel/generate_cc.bzl

bazel/grpc_build_system.bzl

binding.gyp

build.yaml

config.m4

config.w32

doc/environment_variables.md

examples/BUILD

gRPC-Core.podspec

grpc.gemspec

include/grpc++/impl/codegen/config_protobuf.h

include/grpc++/impl/codegen/core_codegen.h

include/grpc++/impl/codegen/core_codegen_interface.h