Merge remote-tracking branch 'upstream/master'

Makefile

setup.py

src/compiler/python_generator.cc

src/compiler/python_generator.h

src/compiler/python_plugin.cc

src/core/census/initialize.c

src/core/iomgr/pollset_multipoller_with_epoll.c

src/csharp/Grpc.Core.Tests/Internal/AsyncCallTest.cs

src/csharp/Grpc.Core.Tests/PInvokeTest.cs

src/csharp/Grpc.Core/Grpc.Core.csproj

src/csharp/Grpc.Core/GrpcEnvironment.cs

src/csharp/Grpc.Core/Internal/AsyncCall.cs

src/csharp/Grpc.Core/Internal/AsyncCallBase.cs

src/csharp/Grpc.Core/Internal/AsyncCallServer.cs

src/csharp/Grpc.Core/Internal/AsyncCompletion.cs

src/csharp/Grpc.Core/Internal/BatchContextSafeHandle.cs

src/csharp/Grpc.Core/Internal/CStringSafeHandle.cs

src/csharp/Grpc.Core/Internal/CallCredentialsSafeHandle.cs

src/csharp/Grpc.Core/Internal/CallSafeHandle.cs

src/csharp/Grpc.Core/Internal/ChannelArgsSafeHandle.cs