Merge branch 'master' into make_clang_great_again_v2

BUILD

Makefile

binding.gyp

build.yaml

config.m4

gRPC.podspec

grpc.gemspec

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

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

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

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

include/grpc++/impl/proto_utils.h

include/grpc++/security/auth_context.h

include/grpc++/security/auth_metadata_processor.h

include/grpc++/security/credentials.h

include/grpc++/security/server_credentials.h

include/grpc/census.h

include/grpc/impl/codegen/propagation_bits.h

include/grpc/support/atm_gcc_atomic.h

include/grpc/support/subprocess.h