merge revision(s) r45462,r45463,r45466: [Backport #9684]

	* struct.c (not_a_member): extract name error and use same error
	  messages.  based on the patch by Marcus Stollsteimer <sto.mar AT
	  web.de> at [ruby-core:61721].  [Bug #9684]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@46673 b2dd03c8-39d4-4d8f-98ff-823fe69b080e