ncos tests assume an inaccurate result

[pjaaskel]

It seems ncos (and other native fp instructions) are very vaguely specified regarding their accuracy. However, at least ncos tests assume something of the result rounding. When implementing ncos with libm cosf(), there's a failure:

...
Validating buffer dst with expected values dst.data(method: ulps=8192.5)
  [ 0]:      0.540302277 (0x3f0a5140) (exp.      0.540302277 (0x3f0a5140), ulps difference                         0 )
  [ 1]:                1 (0x3f800000) (exp.                1 (0x3f800000), ulps difference                         0 )
  [ 2]:                1 (0x3f800000) (exp.                1 (0x3f800000), ulps difference                         0 )
  [ 3]:      0.540302277 (0x3f0a5140) (exp.      0.540302277 (0x3f0a5140), ulps difference                         0 )
  [ 4]:                +qNAN(0) (0x7fc00000) (exp.                +qNAN(0) (0x7fc00000), ulps difference                         0 )
  [ 5]:  -4.37113883e-08 (0xb33bbd2e) (exp.                0 (0x00000000), ulps difference                3007036718*)
  [ 6]:      0.707106769 (0x3f3504f3) (exp.      0.707106769 (0x3f3504f3), ulps difference                         0 )
  Error: failed 1 / 7 comparisons, max ulps error 3007036718 at [ 5].
FAILED: prm/core/arithmetic/nativefp/ncos/ncos_f32_00000 0.11s

The tested input value for [5] is -1.57079637. Because the specs is so vague of the accuracy of these instructions, I do not immediately know how to fix these tests as there doesn't seem to be accompanying runtime API to queries for asking the Agent specific accuracy either.

[atamazov]

Runtime API query for this looks like overkill. Perhaps it is worth to change comparison mode from "ulps" (which can yield enormously big diff) to "relative", with quite relaxed precision requirement, so the test will perform very rude assessment of ncos/nsin. Another option is to exclude nsin/ncos from testing unless explicitly specified by command-line option (together with expected precision).