Refine some test for math function

Refine some test for math function

1. nextafter: we originally use nextafter as cpu execution result, It's return value is double, so changed it to nextafterf.
2. sinpi: add judgement to reduce input data limitation from [-2pi,2pi] to [-pi,pi]
3. cospi: define cospi function.
4. tanpi: define tanpi function by using sinpi/cospi.

Signed-off-by: Yi Sun <yi.sun@intel.com>
Signed-off-by: YangweiX Shui <yangweix.shui@intel.com>