Move the RNG quality checks to a separate file to avoid memory allocation
failures because the random tests are running parallely with other
tests. These tests are marked as SERIAL so they are running
serially.

* Fix rounding of some operations by using fused operations like sincospi
  and fma instead of a multiply add.
* Convert half constants to hex values and use __ushort_as_half
  to avoid redundant conversions from float
* Pass integers instead of pointers in the OpenCL backend of
  the rng functions