mmap(2) on macOS

The text 5b5bec716d0e, as OS X 10.11.6, OS X 10.11.5, OS X 10.11.4, OS X 10.11.3, OS X 10.11.2, OS X 10.11.1, OS X 10.11 shipped it.

allocate memory, or map files or devices into memory

mmap(2) on macOS now