merge revision(s) 41558: [Backport #8561]

	* ext/etc/etc.c (etc_getpwnam): use PRIsVALUE in format string instead
	  of %s and RSTRING_PTR

	* ext/etc/etc.c (etc_getgrnam): ditto


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@41575 b2dd03c8-39d4-4d8f-98ff-823fe69b080e