It isn't set by default on Linux either and it makes the tempnam libc
function always create the temporary file in /tmp rather than prefer the
caller indicated location.

This makes it easier to make driver changes. And in the future other
recipes could potentially benefit from the same infrastructure too.

Without this the virtual addresses will not match the file offsets for
the final initfs blob on AArch64 as there it will align to 64k by
default.

This helps with debugging panics.

This will allow moving the system init configs to this place, keeping
/etc/init.d for local overrides.

Adds `stat` to list of commands to build.