Use sel4-config crate plus minor fixes
- Use sel4-config crate, call it in build.rs, and import generated sel4-config.rs in lib.rs
- x64: Calculate VADDR_LIMIT correctly for x86 when CONFIX_MAX_NUM_NODES > 1
Waiting on sel4-config!2 (merged)
Waiting on sel4-config!2 (merged)