Rollup of 5 pull requests#67503

Closed

Centril wants to merge 49 commits intorust-lang:masterfrom

Centril:rollup-betaed7

Commits on Dec 18, 2019

Reenable static linking of libstdc++ on windows-gnu
mati865
committed

Commits on Dec 19, 2019

Commits on Dec 20, 2019

`SliceKind::VarLen`: make doc-comment render correctly.
Centril
committed

Commits on Dec 21, 2019