[v3] Patch to twister_rand_gen_* to use tr1::random

[Paolo Carlini]

Paolo Carlini wrote:

> the below should most of the runtime fails which we are seeing on 
> 64-bit machines for ext/pb_ds/regression/*rand, for sure does so on 
> ia64-linux. For the latter one remains but first blush seems a 
> different issue:
>
> terminate called after throwing an instance of 
> 'pb_ds::test::forced_exception'
> FAIL: ext/pb_ds/regression/priority_queue_rand.cc execution test

FYI, the above really seems a miscompilation on ia64-linux: only happens 
on that target and only at -O2, not at -O1 or -O0.

Paolo.