Rollup merge of rust-lang#68421 - ehuss:update-cargo-books, r=alexcrichton

Update cargo, books

## cargo

9 commits in ad3dbe10e1e654fb1f032a5dd9481d7cbaa00d65..f6449ba236db31995255ac5e4cad4ab88296a7c6
2020-01-13 21:37:15 +0000 to 2020-01-21 16:15:39 +0000
- Fix wrong directories in host_libdir. (rust-lang/cargo#7798)
- Update humantime requirement from 1.2.0 to 2.0.0 (rust-lang/cargo#7815)
- Fix doc_target test which no longer works on stable/beta. (rust-lang/cargo#7817)
- Fix some erroneous em-dashes in man pages. (rust-lang/cargo#7814)
- fix some clippy warnings (rust-lang/cargo#7808)
- Don't assume iowait always increases on Linux (rust-lang/cargo#7803)
- Add and update some doc comments. (rust-lang/cargo#7800)
- Consistently use em-dash in environment documentation page. (rust-lang/cargo#7799)
- Load credentials only when needed (rust-lang/cargo#7774)

## reference

3 commits in e115753..11e893f
2019-12-22 13:13:14 +0100 to 2020-01-18 21:24:08 +0100
- Small improvements to types/pointer.md (rust-lang/reference#726)
- repr(transparent): mention align=1 requirement (rust-lang/reference#737)
- Elaborate on how to use an extern static correctly (rust-lang/reference#736)

## book

4 commits in 5c5cfd2e94cd42632798d9bd3d1116133e128ac9..87dd6843678575f8dda962f239d14ef4be14b352
2019-12-16 09:27:21 -0600 to 2020-01-20 15:20:40 -0500
- Fix listing numbers (rust-lang/book#2227)
- Move `async` and `await` keywords to 'Currently in Use' (rust-lang/book#2140)
- More cleanup - remove unneeded files (rust-lang/book#2213)
- Small cleanups extracted from the bigger pr i'm working on (rust-lang/book#2212)

## rust-by-example

1 commits in 1d59403cb5269c190cc52a95584ecc280345495a..1c2bd024d13f8011307e13386cf1fea2180352b5
2019-12-27 08:27:05 -0300 to 2020-01-20 12:18:36 -0300
- CamelCase -> UpperCamelCase (rust-lang/rust-by-example#1302)

## embedded-book

1 commits in 9493b7d4dc97eda439bd8780f05ad7b234cd1cd7..4d78994915af1bde9a95c04a8c27d8dca066232a
2019-12-27 20:05:00 +0000 to 2020-01-14 08:25:25 +0000
- Update .gitattributes  (rust-embedded/book#221)

Author: Centril

Cargo.lock

@@ -307,7 +307,7 @@ dependencies = [
  "glob",
  "hex 0.4.0",
  "home",
- "humantime",
+ "humantime 2.0.0",
  "ignore",
  "im-rc",
  "jobserver",
@@ -1013,7 +1013,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "aafcde04e90a5226a6443b7aabdb016ba2f8307c847d524724bd9b346dd1a2d3"
 dependencies = [
  "atty",
- "humantime",
+ "humantime 1.3.0",
  "log",
  "regex",
  "termcolor",
@@ -1026,7 +1026,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "44533bbbb3bb3c1fa17d9f2e4e38bbbaf8396ba82193c4cb1b6445d711445d36"
 dependencies = [
  "atty",
- "humantime",
+ "humantime 1.3.0",
  "log",
  "regex",
  "termcolor",
@@ -1454,6 +1454,12 @@ dependencies = [
  "quick-error",
 ]
 
+[[package]]
+name = "humantime"
+version = "2.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b9b6c53306532d3c8e8087b44e6580e10db51a023cf9b433cea2ac38066b92da"
+
 [[package]]
 name = "hyper"
 version = "0.12.31"
@@ -2647,7 +2653,7 @@ dependencies = [
  "clap",
  "derive_more",
  "env_logger 0.6.2",
- "humantime",
+ "humantime 1.3.0",
  "lazy_static 1.3.0",
  "log",
  "rls-span",