merge revision(s) 34270: [Backport #5858]

	* string.c (rb_str_concat): set array element after definition
	  to fix compile error with Fujitsu C Compiler 5.6 on Solaris 10
	  on Sparc.  [Bug #5878] [ruby-dev:45123]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@40229 b2dd03c8-39d4-4d8f-98ff-823fe69b080e