[PATCH v2] libstdc++: Make certain exceptions transaction_safe.

[Torvald Riegel]

On Thu, 2016-01-21 at 11:00 +0100, Dominique d'Humières wrote:
> Torvald,
> 
> Now that I can bootstrap on darwin, I have found the following failure for libitm.c++/libstdc++-safeexc.C
> 
> /opt/gcc/work/libitm/testsuite/libitm.c++/libstdc++-safeexc.C:50:2: error: unsafe function call 'std::underflow_error::underflow_error(const string&)' within atomic transaction
>   throw T (what);
>   ^~~~~

Well, yes, that's my oversight.  The previous fix disabled the support,
so we need to now xfail or disable this test on Darwin.  Same for AIX.
Ignore these failures for now.  I'll work on a fix.