man: reference RestartForceExitStatus= from the Restart= description
exit-status: rename ExitStatusSet's "code" field to "status"

We should follow the naming scheme waitid() uses, not come up with our
own reversed one...
shared: rename ARCH_TUPLE to LIB_ARCH_TUPLE

This is really just about library locations, hence clarify that we don't
assume this to be anything but that.
update TODO
core: introduce exit_status_set_is_empty() to make things a bit easier to read
shared: add LIB_ARCH tuples for BE ARM archs
test: print library tuple in test
architecture: add tuple for old arm abi

I don't have suitable hardware at hand, so this is based
on debian documentation:

https://wiki.debian.org/ArmEabiPort#GCC_preprocessor_macros_for_floating_point