A few more tests for posix extended alternation

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@109107 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/regex b/include/regex
index 68096b0..fef3594 100644
--- a/include/regex
+++ b/include/regex
@@ -1596,10 +1596,10 @@
 __alternate<_CharT>::__exec_split(bool __second, __state& __s) const
 {
     __s.__do_ = __state::__accept_but_not_consume;
-    if (!__second)
-        __s.__node_ = this->first();
-    else
+    if (__second)
         __s.__node_ = this->second();
+    else
+        __s.__node_ = this->first();
 }
 
 // __begin_marked_subexpression