fix: windows build

packages/grpc-tools/CMakeLists.txt

@@ -1,17 +1,21 @@
-cmake_minimum_required(VERSION 3.6)
+cmake_minimum_required(VERSION 3.15)
 if(COMMAND cmake_policy)
   cmake_policy(SET CMP0003 NEW)
 endif(COMMAND cmake_policy)
 
+# MSVC runtime library flags are selected by an abstraction.
+if(COMMAND cmake_policy AND POLICY CMP0091)
+  cmake_policy(SET CMP0091 NEW)
+endif()
+
 set(CMAKE_CXX_STANDARD 11)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
-set(PROTOBUF_ROOT_DIR ${CMAKE_CURRENT_SOURCE_DIR}/deps/protobuf)
-add_subdirectory(${PROTOBUF_ROOT_DIR}/cmake deps/protobuf)
-
 set(protobuf_BUILD_TESTS OFF CACHE BOOL "Build protobuf tests")
 set(protobuf_WITH_ZLIB OFF CACHE BOOL "Build protobuf with zlib.")
+set(PROTOBUF_ROOT_DIR ${CMAKE_CURRENT_SOURCE_DIR}/deps/protobuf)
+add_subdirectory(${PROTOBUF_ROOT_DIR}/cmake deps/protobuf)
 
 set(CMAKE_EXE_LINKER_FLAGS "-static-libstdc++")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-stack-protector")
@@ -22,7 +26,7 @@ add_executable(grpc_node_plugin
 )
 
 if (MSVC)
-  add_definitions(/MTd)
+  set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreaded$<$<CONFIG:Debug>:Debug>)
 endif (MSVC)
 
 target_include_directories(grpc_node_plugin
@@ -34,4 +38,4 @@ target_include_directories(grpc_node_plugin
 target_link_libraries(grpc_node_plugin
   libprotoc
   libprotobuf
-)
+)