Rollup merge of #69667 - JohnTitor:no-debug, r=nikomatsakis

Remove the `no_debug` feature

Context: https://github.com/rust-lang/rust/issues/29721#issuecomment-367642779

r? @nikomatsakis

diff --cc src/librustc_feature/active.rs
Simple merge

diff --cc src/librustc_feature/builtin_attrs.rs
Simple merge

diff --cc src/librustc_typeck/collect.rs
Simple merge