[v3] c++0x common_type, <ratio> and <chrono>

[Paolo Carlini]

> Oh it might be the case that _GLIBCXX_USE_C99_STDINT_TR1 is not defined which
> means it is not being tested at all :).  I guess the testcase needs to
> take that into account when it does dg-error .

Oh, boring, I think we need a check_v3_target_stdint because of that. I'll do it... The only consolation if that those testcases will not have the #ifdefs, will be cleaner.

Paolo.