Merge branch 'master' into source_cleanup

Makefile

build.json

include/grpc/support/thd.h

include/grpc/support/thd_posix.h

include/grpc/support/thd_win32.h

include/grpc/support/time.h

include/grpc/support/time_posix.h

include/grpc/support/time_win32.h

src/core/support/sync_posix.c

src/core/support/thd_posix.c

src/core/support/thd_win32.c

src/core/support/time.c

src/core/support/time_posix.c

src/core/tsi/ssl_transport_security.c

src/cpp/server/async_server_context.cc

src/cpp/server/server_rpc_handler.cc

src/node/ext/timeval.cc

src/php/ext/grpc/call.c

src/php/ext/grpc/call.h

src/php/ext/grpc/server.c