This adds auto-assertion to `rustc_clean/dirty` and also implements
more comprehensive testing for
- src/test/incremental/hashes/enum_constructors.rs
- src/test/incremental/hashes/enum_defs.rs
- src/test/incremental/hashes/extern_mods.rs
- src/test/incremental/hashes/inherent_impls.rs
- src/test/incremental/hashes/statics.rs
- src/test/incremental/hashes/struct_constructors.rs
- src/test/incremental/hashes/type_defs.rs
trait_defs.rs and trait_impl.rs are blocked on a hard to triage
compiler ICE (at least hard for a newbie like me) having to do
with some DepNodes not getting computed for traits.
A FIXME has been added in the source to reflect this continued
work.
Instead of collecting all potential inputs to some metadata entry and
hashing those, we directly hash the values we are storing in metadata.
This is more accurate and doesn't suffer from quadratic blow-up when
many entries have the same dependencies.
