Fix cross2d

There were two issues:

- The overload decorator didn't overload `cross2d`
- The tests called the overload directly, rather than calling `cross2d`
  in a jitted function.

numba/np/arraymath.py

@@ -4620,7 +4620,7 @@ def cross2d(a, b):
     pass
 
 
-@overload
+@overload(cross2d)
 def cross2d_impl(a, b):
     if not type_can_asarray(a) or not type_can_asarray(b):
         raise TypingError("Inputs must be array-like.")

numba/tests/test_np_functions.py

@@ -382,6 +382,10 @@ def np_cross(a, b):
     return np.cross(a, b)
 
 
+def nb_cross2d(a, b):
+    return cross2d(a, b)
+
+
 def flip_lr(a):
     return np.fliplr(a)
 
@@ -4432,7 +4436,7 @@ def test_cross_exceptions(self):
 
     def test_cross2d(self):
         pyfunc = np_cross
-        cfunc = cross2d
+        cfunc = njit(nb_cross2d)
         pairs = [
             # 2x2 (n-dims)
             (
@@ -4477,7 +4481,7 @@ def test_cross2d(self):
             self.assertPreciseEqual(expected, got)
 
     def test_cross2d_exceptions(self):
-        cfunc = cross2d
+        cfunc = njit(nb_cross2d)
         self.disable_leak_check()
 
         # test incompatible dimensions for ndim == 1