Prepare 0.9.0 release (rust-random#1558)

Enable `stdarch_x86_avx512` for cpu has `avx512bw` (rust-random#1551)

Enable `stdarch_x86_avx512` for cpu has `avx512bw` (rust-random#1551)

Update: getrandom v0.3.0 rc.0 (rust-random#1541)

Update: getrandom v0.3.0 rc.0 (rust-random#1541)

Fix docs.rs build options (rust-random#1539)

Prepare 0.9.0-beta.0 (rust-random#1535)

- Update version numbers
- Update CHANGELOGs
- Add an extra benchmark

Prepare 0.9.0-beta.0 (rust-random#1535)

- Update version numbers
- Update CHANGELOGs
- Add an extra benchmark

rand_distr 0.5.0-alpha.3 - fix doc build

Include tests in rand package