This will allow for e.g. xous on riscv32-imac but not a precursor
target, for example: by using feature selectors we get to have
a bigger range of targets that we support, such as for implementations
that haven't been upstreamed or have official target-triples.
The downsides are:
- patch override libraries don't absorb feature flags. so, for
example, the AES crate that is used to patch other crates won't
be aware of the target features without modifying the referencing
crates.
- features are normally meant to be additive, but target features
are mutually exclusive. The mutex is enforced by a check in
utralib that throws a panic on build if two targets are accidentally
selected at the same time.
This is in a bid to gain CBC crate compatibility which requires
at least an AES 0.8 API level.
It breaks a lot of stuff, which is fixed in the next commit.
- inverted text indicates a trusted message. policy is enforced in the GAM.
- we don't have a way to lock the USB port yet; but at least now it's communicated.
