clean the Debug impl for CrateNum and DefId

[arielb1]

Just a tiny quality-of-life improvement because I got tired of noisy debug logs.

before: DefId { krate: CrateNum(11), index: DefIndex(0:6) => foo[8787]::Mapper[0]::OtherType[0] } }
after: {crate11:0:6 ~ foo[8787]::Mapper[0]::OtherType[0]})

r? @michaelwoerister

[arielb1]

@bors rollup

[kennytm]

The mir-opt tests need to be updated for the new representation.

[00:56:38] failures:
[00:56:38]     [mir-opt] mir-opt/validate_1.rs
[00:56:38]     [mir-opt] mir-opt/validate_4.rs
[00:56:38]     [mir-opt] mir-opt/validate_5.rs

[michaelwoerister]

I like the idea. I think the concrete format could be improved though. In particular crate11:0:6 is a bit confusing. I'd either like it more concise:

after: {11.0.6 ~ foo[8787]::Mapper[0]::OtherType[0]})

Or a bit more self-explanatory:

after: {DefId(11/0:6) ~ foo[8787]::Mapper[0]::OtherType[0]}

[michaelwoerister]

@bors r+

[bors]

📌 Commit e7c8fbf has been approved by michaelwoerister