Squashed 'rbenv/plugins/ruby-build/' changes from b998838..4ef4ed4

4ef4ed4 Merge pull request #633 from sstephenson/upgrade-instructions
5285456 Merge pull request #635 from sstephenson/add-checksums
92d9cf8 Add missing checksums to Rubinius definitions
b14f8c0 Fill in TRAVIS_COMMIT_RANGE if missing
e754d67 Fix test to compensate for different `ls` output on Fedora/Centos
32a825c Merge branch 'os-release'
406d745 Peruse `/etc/os-release` among others when detecting system info
aa4a237 Show specific upgrade instructions based on environment
b275e87 Merge pull request #632 from sstephenson/definitions-completion
56c8f29 `rbenv install` completion includes definitions from plugins
aaf50ec Fix `brew-publish` script that's part of release process
512910a ruby-build 20140908
0170728 Merge pull request #630 from sstephenson/freebsd-make
c2eb5e2 Merge pull request #631 from sstephenson/sort-versions
323c2b7 Sort Ruby versions when listing available definitions
274838b Merge branch 'tmp-noexec'
a4556a7 Verify that TMPDIR can hold executables before installing
60a5abe Fix stripping away non-digits from OS release number
0e58079 On FreeBSD, stop defaulting to MAKE=gmake
29f1a19 Merge branch 'pr-checksum'
66fd3ec Merge branch 'freebsd-cpu'
95b32ac Improve `script/mirror` argument handling
3add5c4 Verify checksums for pull requests from other people
f4c2fe6 Fix detecting of CPU cores on FreeBSD
bff583b Merge pull request #626 from sstephenson/build-output
4463320 Print OS information on build failure
95964b1 Highlight output that mentions path to full build log
17cb1ed Prevent "BUILD FAILED" appearing twice on `./configure` error
0bdd502 Indicate ruby-build version number on build failures
2f51dee Print configure options when openssl ext failed to compile
1fa109c Don't log files as they're extracted from tarball

git-subtree-dir: rbenv/plugins/ruby-build
git-subtree-split: 4ef4ed4cd15e9722527e96f782b79b4a20025965
Merge commit '94490af2ac5a6ee34fb0ab27f6f90984bd0bb5c6'

Pull sstephenson/ruby-build to `rbenv/plugins/ruby-build`.