Use mersenne twister for random values.

We now use the 64 bit mersenne twister algorithm to generate 64 bit
random values.

The main advantage is that this is C++11 compatible and will work under
msvc as well.

Bug: 186567864
Change-Id: I0f7013a641d7dc211ef7e4eb4f042b4235116fc4
Test: Launch rootcanal, see gDevice beacon show up