Created originally on Bitbucket by lunixbochs (Ryan Hileman)
This allows PyPy to be codesigned with Hardened Runtime on macOS Mojave with
com.apple.security.cs.allow-jit instead of
com.apple.security.cs.allow-unsigned-executable-memory by mapping executable pages using the MAP_JIT flag to mmap. I’ve confirmed this flag exists at least back to 10.11 (El Capitan). I don’t know exactly how these defines get codegen'd so I’m not sure if I handled the linux/windows compilation case correctly.