Random nucleation on a CPU
When using the random nucleation (NucStatConstantNucleationStatus::random), the code supposes to select a variant number randomly at each grid point (i,j,k). The phi of the selected variant becomes 0.5, and the others are set to 0.
On the CPU, the selected variant number is the same currently, and thus it needs to be updated.
On the GPU, it selects a number randomly as expected.