Test fixes from the rollup

Closes #13546 (workcache: Don't assume gcc exists on all platforms)
Closes #13545 (std: Remove pub use globs)
Closes #13530 (test: Un-ignore smallest-hello-world.rs)
Closes #13529 (std: Un-ignore some float tests on windows)
Closes #13528 (green: Add a helper macro for booting libgreen)
Closes #13526 (Remove RUST_LOG="::help" from the docs)
Closes #13524 (dist: Make Windows installer uninstall first. Closes #9563)
Closes #13521 (Change AUTHORS section in the man pages)
Closes #13519 (Update GitHub's Rust projects page.)
Closes #13518 (mk: Change windows to install from stage2)
Closes #13516 (liburl doc: insert missing hyphen)
Closes #13514 (rustdoc: Better sorting criteria for searching.)
Closes #13512 (native: Fix a race in select())
Closes #13506 (Use the unsigned integer types for bitwise intrinsics.)
Closes #13502 (Add a default impl for Set::is_superset)