Closes gh-1278

Provides an alternative implementation of std::abs for complex types
via std::hypot which is used on Windows.

Author: oleksandr-pavlyk

dpctl/tensor/libtensor/include/kernels/elementwise_functions/abs.hpp

@@ -25,6 +25,7 @@
 #pragma once
 #include <CL/sycl.hpp>
 #include <cmath>
+#include <complex>
 #include <cstddef>
 #include <cstdint>
 #include <type_traits>
@@ -72,9 +73,25 @@ template <typename argT, typename resT> struct AbsFunctor
             return x;
         }
         else {
-            return std::abs(x);
+            if constexpr (is_complex<argT>::value) {
+                return cabs(x);
+            }
+            else {
+                return std::abs(x);
+            }
         }
     }
+
+private:
+    template <typename realT> realT cabs(std::complex<realT> const &z)
+    {
+#ifdef _WINDOWS
+        // work-around for gh-1279
+        return std::hypot(std::real(z), std::imag(z));
+#else
+        return std::abs(z);
+#endif
+    }
 };
 
 template <typename argT,