There are none of them in `libc` except for `__progname` on Android, but
that one cannot be tested because it's not present in any header files.

Looks like Travis has moved on from our old images, so we're forced to
update.

The mmap(2) flag indicate that the mapping is used as a stack.

https://man.openbsd.org/mmap.2#MAP_STACK
https://marc.info/?l=openbsd-tech&m=152035796722258&w=2

Was able to move some of them up one level so they are valid on more
platforms with less duplication

CI still runs version 10

Available since FreeBSD 9.0, this API allows using local descriptors
instead of global PIDs. It works in Capsicum sandboxes.