a build.rs helper library that parses your target string and sets some useful cfg's for you.

```text
cargo:rustc-cfg=arm_architecture="v7-r"
cargo:rustc-check-cfg=cfg(arm_architecture, values("v6-m", "v7-m", "v7e-m", "v8-m.base", "v8-m.main", "v7-r", "v8-r", "v7-a", "v8-a"))
cargo:rustc-cfg=arm_isa="A32"
cargo:rustc-check-cfg=cfg(arm_isa, values("A64", "A32", "T32"))
cargo:rustc-cfg=arm_endianness="little"
cargo:rustc-check-cfg=cfg(arm_endianness, values("little", "big"))
cargo:rustc-cfg=arm_float_abi="hard"
cargo:rustc-check-cfg=cfg(arm_float_abi, values("soft", "hard"))
```