Ok I see, you are adding this to the top level CMakeLists in the samples. So in that top level file you need to replace your new command with this one on the same line:
add_compile_definitions(_GLIBCXX_USE_CXX11_ABI=0)
So to be clear in the post I linked to there are three options, the one you tried to do there is adding to a specific target CMakeLists file. The other two options are to do what I suggest in this post or add this to the CMake toolchain file.