[SYCL] tests to support new sycl::span deduction guide fix

SYCL/Basic/span.cpp

@@ -104,9 +104,22 @@ void testSpanOnDevice() {
   }
 }
 
+void testSpanDeclarations() {
+  // test the various declarations, especially unqualified ones.
+  // should compile
+  int arr[]{1, 2, 3, 4};
+  const int constArr[]{8, 7, 6};
+  sycl::span fromArray{arr};
+  sycl::span fromConstArray{constArr};
+
+  std::vector<int> vec(4);
+  sycl::span fromVec{vec};
+}
+
 int main() {
   testSpanCapture();
   testSpanOnDevice();
+  testSpanDeclarations();
 
   return 0;
 }