Merge branch 'cleaner-posix2' into cleaner-posix3

BUILD

CONTRIBUTING.md

INSTALL.md

Makefile

build.yaml

composer.json

examples/README.md

examples/cpp/README.md

examples/php/README.md

examples/php/composer.json

examples/php/greeter_client.php

examples/php/route_guide/route_guide_client.php

examples/python/route_guide/route_guide_server.py

gRPC.podspec

grpc.gemspec

include/grpc++/alarm.h

include/grpc++/channel.h

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

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

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