merge revision(s) 46481: [Backport #9966]

	* encoding.c (enc_find): [DOC] never accepted a symbol.
	  [ruby-dev:48308] [Bug #9966]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@46670 b2dd03c8-39d4-4d8f-98ff-823fe69b080e