Fix security exception for the MSVC2010+ compilers (#3438)

Author: szekerest

mapscript/csharp/CMakeLists.txt

@@ -18,9 +18,9 @@ if (WIN32)
     endif(CMAKE_CL_64)
 	set (KEYFILE_SPEC /keyfile:${PROJECT_SOURCE_DIR}\\mapscript\\csharp\\mapscript.snk)
   endif (NOT MSVC71)
-  if (MSVC10)
+  if (MSVC_VERSION GREATER 1500)
       set(PLATFORM_TARGET ${PLATFORM_TARGET} /define:CLR4)
-  endif (MSVC10)
+  endif (MSVC_VERSION GREATER 1500)
 endif(WIN32)
 
 MARK_AS_ADVANCED(CSHARP_COMPILER)