Do not statically link _ctypes_test module #721
Description
It (intentionally) exports a bunch of C symbols with unprefixed names like left, right, top, bottom, myprintf, an_integer, getSPAMANDEGGS, etc. We shouldn't be exporting these symbols in bin/python or libpython.
We probably want to keep building it for the sake of running the tests that use it, we just want to build it dynamically.
It might be cool to add a test at the same time that all our exported dynamic symbols start with Py or _Py. There is some stuff in src/validation.rs to check what we're doing with symbols but I guess it doesn't check this.