libyaml 0.1.6

Closes a security vulnerability:
http://www.ocert.org/advisories/ocert-2014-003.html
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-2525
libyaml: update 0.1.6 bottle.

Closes #27923.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
Fix Keg#find so we don't have to deal with it everywhere

lol inheritance
Put constant strings in a constant
Don't mix boolean operator types
Fix overly defensive handling of src parameter in make_relative_symlink

This method is for internal use only. It is unsuitable for use in
formulae, which should use install_symlink to create relative symlinks.
Thus callers are required to pass a Pathname, not a string, and we can
remove this conditional.

Further, if src is not absolute, then src.relative_path_from(dirname)
will fail. All callers currently pass absolute pathnames. Therefore we
don't need to call expand_path when printing it.
Return early so we can reduce nesting of conditionals
aria2 1.18.4
mono: use the patch submitted upstream instead of a custom post build fix
mono: update 3.2.8 bottle.