merge revision(s) r46783: [Backport #6716]

	* lib/fileutils.rb: handle ENOENT error with symlink targeted to
	  non-exists file. [ruby-dev:45933] [Bug #6716]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@47953 b2dd03c8-39d4-4d8f-98ff-823fe69b080e