removed C++11 modifier

CMakeLists.txt

@@ -38,11 +38,7 @@ target_include_directories(assimp PRIVATE
     . # for <contrib/zlib/zlib.h>
 )
 
-if(NOT MSVC)
-        target_compile_options(assimp PRIVATE
-        $<$<COMPILE_LANGUAGE:CXX>:-std=c++11>
-    )
-else()
+if(MSVC)
     target_compile_options(assimp PUBLIC
         /MP # multi processor compilation
     )