Apparently quiet_system isn't always quiet

cf. #28918.
ldns: install pkg-config file
ldns: update 1.6.17 bottle.
vim 7.4.273
Use File::PATH_SEPARATOR
Set ENV variables to strings, not pathnames
`require` accepts Pathnames
No need to put vendor on the load path
Simplify HOMEBREW_LIBRARY_PATH usage
Remove obsolete fallback for broken Xcode 4.3+

After recent cleanups the code in this branch should be unreachable, so
there is little point in keeping it around.
Simpler Xcode prefix detection code
doctor: use Xcode.bundle_path
cantera: use ENV.append
libtomcrypt: use ENV.append
spidermonkey: drop really old workaround

This was added in 2009 to a completely different version of the formula.
twemcache: use ENV.append
hercules --HEAD

Closes #28922.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
mailutils 2.2

Closes #28893.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
mercurial 3.0

Closes #28916.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
Fix for String#undent

Without it, String#undent would fail on unindented strings, e.g.:

    "foo".undent

NoMethodError: undefined method `length' for nil:NilClass`

Closes #28873.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>