[v3] Start random dists values testing

[Paolo Carlini]

Hi,

> The test compiles  and runs if I add -D_GLIBCXX_USE_C99_MATH_TR1:

Unfortunately I cannot debug the issue over the next few hours. If you are willing to further help I suggest checking why the dg-require I addes and used exactly because of that doesn't automatically skip the testcase on targets not defining the macro, probanly it's something trivial like a typo (in that case a fix is preapproved)
> 


Paolo