[libstdc++ testsuite][patch] many locale tests only SUPPORTED on linux, start making these portable

[Tim Shen]

Speaking of locale, I still have no clue how to implement
std::regex_traits::transform_primary. Do we always use glibc as a
"backend" for locale representation?

I asked this in libc-alpha but didn't do enough follow ups :(
https://sourceware.org/ml/libc-alpha/2014-03/msg00937.html

I'm not sure what to do though...


-- 
Regards,
Tim Shen