merge revision(s) 41347: [Backport #5048] [Backport #5465] [Backport #8319]

	* ext/tk/extconf.rb: support s390x (Thanks to bkabrda) [ruby-trunk - Bug #5465]
	* ext/tk/extconf.rb: apply [Backport87 - Backport #5048]
	* ext/tk/lib/tk/canvas.rb, ext/tk/sample/demos-{en,jp}/{tree.rb,widget}: fix bug (Thanks to zzak) [ruby-trunk - Bug #8319]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@41362 b2dd03c8-39d4-4d8f-98ff-823fe69b080e