Get isfinite, isinf, and isnan right in jerry-math (#4497)

- `finite` is not C99 but a BSD fp classification function, so it
  is removed.
- The standard specifies that `isnan` is a macro (just like
  `isfinite` and `isinf`), so the `isnan` function implementation
  is removed.
- `isfinite` incorrectly classified NAN as finite, which is fixed.
- `isinf` returned 1 for negative infinity. This is not a bug
  according to the standard, but is not aligned with recent glibc,
  which returns -1. This is changed to simplify testing.
- Added test cases for `isfinite` and `isinf` to the unit test of
  jerry-math.
- Added a new pass to unittests to ensure that jerry-math is
  tested.

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu

jerry-math/jerry-math-internal.h

@@ -112,9 +112,6 @@ double fabs (double x);
 double floor (double x);
 double fmod (double x, double y);
 
-int isnan (double x);
-int finite (double x);
-
 double nextafter (double x, double y);
 
 /*