Attempt to get rid from warning in ManhattanStyle under windows

GUI/externals/qt-manhattan-style/CMakeLists.txt

@@ -53,15 +53,6 @@ set(SRCS
     extensions/threelevelsitempicker.cpp
 )
 
-if(MSVC)
-foreach (flag_var
-         CMAKE_CXX_FLAGS CMAKE_CXX_FLAGS_DEBUG CMAKE_CXX_FLAGS_RELEASE
-         CMAKE_CXX_FLAGS_MINSIZEREL CMAKE_CXX_FLAGS_RELWITHDEBINFO)
-
-    string(REPLACE "/MD" "-MT" ${flag_var} "${${flag_var}}")
-endforeach()
-endif()
-
 set(include_dirs ${CMAKE_CURRENT_SOURCE_DIR})
 include_directories(${include_dirs})