misc: Use nint/nuint instead of IntPtr/UIntPtr

src/ARMeilleure/IntermediateRepresentation/IntrusiveList.cs

@@ -32,7 +32,7 @@ namespace ARMeilleure.IntermediateRepresentation
         /// <exception cref="ArgumentException"><typeparamref name="T"/> is not pointer sized.</exception>
         public IntrusiveList()
         {
-            if (Unsafe.SizeOf<T>() != IntPtr.Size)
+            if (Unsafe.SizeOf<T>() != nint.Size)
             {
                 throw new ArgumentException("T must be a reference type or a pointer sized struct.");
             }

src/ARMeilleure/IntermediateRepresentation/MemoryOperand.cs

@@ -24,7 +24,7 @@ namespace ARMeilleure.IntermediateRepresentation
         {
             Debug.Assert(operand.Kind == OperandKind.Memory);
 
-            _data = (Data*)Unsafe.As<Operand, IntPtr>(ref operand);
+            _data = (Data*)Unsafe.As<Operand, nint>(ref operand);
         }
 
         public Operand BaseAddress

src/ARMeilleure/IntermediateRepresentation/Operation.cs

@@ -228,7 +228,7 @@ namespace ARMeilleure.IntermediateRepresentation
 
         public readonly override int GetHashCode()
         {
-            return HashCode.Combine((IntPtr)_data);
+            return HashCode.Combine((nint)_data);
         }
 
         public static bool operator ==(Operation a, Operation b)