Compile CpuMathNative and FastTreeNative with charset=utf-8, fix for issue dotnet#78 (dotnet#187)

Author: xadupre

src/Native/CMakeLists.txt

@@ -10,6 +10,7 @@ include_directories("${CMAKE_BINARY_DIR}/../../")
 if(WIN32)
     add_definitions(-DWIN32)
     add_definitions(-D_WIN32=1)
+    add_definitions(-DUNICODE -D_UNICODE)
     if(IS_64BIT_BUILD)
         add_definitions(-D_WIN64=1)
     endif()