[Patch] libstdc++/9548 and DR 231

[Benjamin Kosnik]

>Tested x86-linux. Ok?

This patch looks great Paolo, but single tests only now for the
testsuite, so split 6.cc into 6.cc and 7.cc. ie:

6.cc
+ // libstdc++/9548
+ void test01()

7.cc
+ // DR 231
+ void test02()

No need to repost.

-benjamin