libstdc++/7445: poor performance of std::locale::classic() in multi-threaded applications

[Benjamin Kosnik]

> Is the patch for 7445 going to be reverted before 3.2 goes out then?

No. It's been reverted on the 3.2 branch though, so 3.2.1 won't have it.

We're still waiting on a testcase for this.

-benjamin