* vm.c (vm_set_main_stack): remove unnecessary check.  toplevel
	  binding must be initialized.  [Bug #12611] (N1)

	* win32/win32.c (w32_symlink): fix return type.  [Bug #12611] (N3)

	* string.c (rb_str_split_m): simplify the condition.
	  [Bug #12611](N4)


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@55959 b2dd03c8-39d4-4d8f-98ff-823fe69b080e