try fix c++ vs2017 build
diff --git a/CMakeLists.txt b/CMakeLists.txt
index e8e65d4..26a4a63 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -100,6 +100,8 @@
   add_definitions(-D_WIN32_WINNT=0x600 -D_SCL_SECURE_NO_WARNINGS -D_CRT_SECURE_NO_WARNINGS -D_WINSOCK_DEPRECATED_NO_WARNINGS)
   # needed to compile protobuf
   add_definitions(/wd4065 /wd4506)
+  # TODO(jtattermusch): revisit warnings disabled when upgrading to protobuf3.6.0
+  add_definitions(/wd4200 /wd4291 /wd4244)
   # TODO(jtattermusch): revisit C4267 occurrences throughout the code
   add_definitions(/wd4267)
   # TODO(jtattermusch): needed to build boringssl with VS2017, revisit later