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

[Paolo Carlini]

> The cons_overflow.cc and ops_overflow.cc testcase fails on
> spu-elf as that target does not have denorms for float (it does for double
> though).

float, double?!? The code actually in only implements <ratio>, which is only about *integer* types (actually only intmax_t + uintmax_t as an implementation detail). Please explain in better detail.

Thanks,
Paolo.