CPU (A64): Add Pmull_V Inst. with Clmul fast path for the "1/2D -> 1Q" variant & Sse fast path and slow path for both the "8/16B -> 8H" and "1/2D -> 1Q" variants; with Test. (#1817)

* Add Pmull_V Sse fast path only, both "8/16B -> 8H" and "1/2D -> 1Q" variants; with Test.

* Add Clmul fast path for the 128 bits variant.

* Small optimisation (save 60 instructions) for the Sse fast path about the 128 bits variant.

* Add slow path, both variants. Fix V128 Shl/Shr when shift = 0.

* A32: Add Vmull_I P64 variant (slow path); not tested.

* A32: Add Vmull_I_P8_P64 Test and fix P64 variant.

ARMeilleure/Instructions/SoftFallback.cs

@@ -1260,5 +1260,22 @@ namespace ARMeilleure.Instructions
                 : (uint)(value >> 32);
         }
 #endregion
+
+        public static V128 PolynomialMult64_128(ulong op1, ulong op2)
+        {
+            V128 result = V128.Zero;
+
+            V128 op2_128 = new V128(op2, 0);
+
+            for (int i = 0; i < 64; i++)
+            {
+                if (((op1 >> i) & 1) == 1)
+                {
+                    result ^= op2_128 << i;
+                }
+            }
+
+            return result;
+        }
     }
 }