Merge github.com:grpc/grpc into metadata_filter

Makefile

README.md

build.yaml

config.m4

doc/negative-http2-interop-test-descriptions.md

include/grpc/support/log_windows.h

package.json

src/core/ext/resolver/dns/native/dns_resolver.c

src/core/ext/transport/chttp2/transport/frame_rst_stream.c

src/php/ext/grpc/call.c

src/php/ext/grpc/call_credentials.c

src/php/ext/grpc/channel_credentials.c

src/php/ext/grpc/php7_wrapper.h

src/php/ext/grpc/php_grpc.h

src/php/ext/grpc/server_credentials.c

src/php/ext/grpc/timeval.c

src/proto/grpc/testing/control.proto

templates/config.m4.template

templates/package.json.template

test/core/support/BUILD