[SYCL] Remove accuracy test for native implementation of math function.

Native implementation doesn't provide any accuracy guarantees, so
checking return value is not portable.
This test fails on the system with GCC 7.3 (default GCC on Ubuntu 18.04).

Signed-off-by: Alexey Bader <alexey.bader@intel.com>

Author: bader

sycl/test/built-ins/vector_math.cpp

@@ -33,26 +33,6 @@ int main() {
     assert(r2 == 0.4f);
   }
 
-  // native::exp
-  {
-    cl::sycl::cl_float2 r{0};
-    {
-      buffer<cl::sycl::cl_float2, 1> BufR(&r, range<1>(1));
-      queue myQueue;
-      myQueue.submit([&](handler &cgh) {
-        auto AccR = BufR.get_access<access::mode::write>(cgh);
-        cgh.single_task<class nexpF2>([=]() {
-          AccR[0] = cl::sycl::native::exp(cl::sycl::cl_float2{1.0f, 2.0f});
-        });
-      });
-    }
-    cl::sycl::cl_float r1 = r.x();
-    cl::sycl::cl_float r2 = r.y();
-    std::cout << "r1 " << r1 << " r2 " << r2 << std::endl;
-    assert(r1 > 2.718 && r1 < 2.719); // ~2.718281828459045
-    assert(r2 > 7.389 && r2 < 7.390); // ~7.38905609893065
-  }
-
   // fabs
   {
     cl::sycl::cl_float2 r{0};