Merge branch 'master' into cpp_races

examples/objective-c/helloworld/main.m

grpc.gemspec

include/grpc/impl/codegen/sync.h

include/grpc/impl/codegen/time.h

setup.py

src/core/iomgr/iocp_windows.c

src/core/iomgr/pollset_posix.c

src/core/support/stack_lockfree.c

src/core/support/sync_win32.c

src/core/support/time.c

src/core/transport/chttp2/writing.c

src/node/ext/timeval.cc

src/objective-c/GRPCClient/private/GRPCChannel.h

src/objective-c/GRPCClient/private/GRPCChannel.m

src/objective-c/GRPCClient/private/GRPCHost.h

src/objective-c/GRPCClient/private/GRPCHost.m

src/python/grpcio/grpc/_cython/_cygrpc/grpc.pxi

src/python/grpcio/grpc/_cython/_cygrpc/records.pyx.pxi

src/python/grpcio/grpc/_cython/cygrpc.pyx

src/python/grpcio/grpc/_cython/imports.generated.h