How do you define the C++ runtime in config.make

I am adding a SO dependency using PROJECT_LDFLAGS in my application’s config.make file. But I am getting undefined dependencies related to std::string (std::__1::char_traits, std::_C_1::allocator >).

I suspect this may be to do with the runtime version not matching that in the .SO. How do you define the runtime (I believe it usually goes in the APP_STL variable in the How is this defined in the OF makefile?