i386_set_ldt(2) on macOS

The text 85af8b94de15, as Mac OS X 10.1.5, Mac OS X 10.1.4, Mac OS X 10.1.3, Mac OS X 10.1.2, Mac OS X 10.1.1, Mac OS X 10.1 shipped it.

manage i386 per-process Local Descriptor Table entries

i386_set_ldt(2) on macOS now