Pybind11 doesn't work or C++ doesn't compile after upgrading to Mojave: -lstdc++ not found

Question

I was able to install the pybind11 example here before I upgraded my MacOS. However, after I upgraded my MacOS to Mojave, when I compile the same example on that link, I see

Answer 1

I actually found the answer. I only needed to do

export MACOSX_DEPLOYMENT_TARGET=10.9

The installation went smoothly.