Rollup of 7 pull requests

[GuillaumeGomez]

• Successful merges: Tweaks to invalid ctor messages #47116, Suggest casting on numeric type error #47247, Only link res_init() on GNU/*nix #47334, Upgrade env_logger #47501, Add E0659 for ambiguous names #47512, On missing method do not suggest private traits #47534, Automaticaly calculate beta prerelease numbers #47582
• Failed merges:

[rust-highfive]

r? @nikomatsakis

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[GuillaumeGomez]

@bors: r+ p=1

[bors]

📌 Commit d9efbd8 has been approved by GuillaumeGomez

[bors]

⌛ Testing commit d9efbd8eaa7b9b82bc53a9691447e8410df2d170 with merge b2ac6b643cc580bc3ed63715c69242332b9dcc9a...

[bors]

💔 Test failed - status-travis

[kennytm]

x86_64-gnu failed, legit.

[01:43:21] WARNING: documentation for this crate may be rendered differently using the new Pulldown renderer.
[01:43:21]     See https://github.com/rust-lang/rust/issues/44229 for details.
[01:43:21] WARNING: rendering difference in ``strftime`/`strptime`-inspired date and time formatting syntax.`
[01:43:21]    --> /cargo/registry/src/git.luolix.top-1ecc6299db9ec823/chrono-0.4.0/src/format/strftime.rs:4:0
[01:43:21]     /html[0]/body[0]/table[0]/tbody[0]/tr[0]/td[1] One element is missing: expected: `strong`
<snip>
[01:43:21] WARNING: rendering difference in ``strftime`/`strptime`-inspired date and time formatting syntax.`
[01:43:21]    --> /cargo/registry/src/git.luolix.top-1ecc6299db9ec823/chrono-0.4.0/src/format/strftime.rs:4:0
[01:43:21]     /html[0]/body[0]/table[0]/tbody[0]/tr[65] Unexpected element `td`: found: `<td><strong>SPECIAL SPECIFIERS:</strong></td>`
[01:43:21] Aborting with 1 rendering differences
[01:43:21] �[m�[m�[31m�[1merror:�[m Could not document `chrono`.

The new chrono is introduced by #47501.