Suppress VS2017 compiler/linker warnings

VS2017 warns about a few additional things, for example, files that
define no symbols (which is typically the result of a platform specific
ifdef not applying on Windows).

Suppress these warnings so the build is clean on VS2017.

cmake/CMakeLists.txt

@@ -135,12 +135,15 @@ endif (protobuf_BUILD_SHARED_LIBS)
 if (MSVC)
   # Build with multiple processes
   add_definitions(/MP)
-  add_definitions(/wd4244 /wd4267 /wd4018 /wd4355 /wd4800 /wd4251 /wd4996 /wd4146 /wd4305 /wd4309)
+  add_definitions(/wd4244 /wd4267 /wd4018 /wd4355 /wd4800 /wd4251 /wd4996 /wd4146 /wd4305 /wd4309 /wd4065 /wd4506 /wd4307 /wd4334)
   # Allow big object
   add_definitions(/bigobj)
   string(REPLACE "/" "\\" PROTOBUF_SOURCE_WIN32_PATH ${protobuf_SOURCE_DIR})
   string(REPLACE "/" "\\" PROTOBUF_BINARY_WIN32_PATH ${protobuf_BINARY_DIR})
   configure_file(extract_includes.bat.in extract_includes.bat)
+  
+  # Suppress linker warnings about files with no symbols defined.
+  set(CMAKE_STATIC_LINKER_FLAGS /ignore:4221)
 endif (MSVC)
 
 get_filename_component(protobuf_source_dir ${protobuf_SOURCE_DIR} PATH)