Auto merge of rust-lang#148280 - jhpratt:rollup-um01cgu, r=jhpratt

Rollup of 8 pull requests

Successful merges:

 - rust-lang#138217 (Turn `Cow::is_borrowed,is_owned` into associated functions.)
 - rust-lang#147858 (Micro-optimization attempt in coroutine layout computation)
 - rust-lang#147923 (Simplify rustc_public context handling)
 - rust-lang#148115 (rustdoc: Rename unstable option `--nocapture` to `--no-capture` in accordance with `libtest`)
 - rust-lang#148137 (Couple of changes for Redox OS)
 - rust-lang#148176 ([rustdoc] Include attribute and derive macros when filtering on "macros")
 - rust-lang#148253 (Handle default features and -Ctarget-features in the dummy backend)
 - rust-lang#148272 (Align VEX V5 boot routine to 4 bytes)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors