Style/consistency/nano-optimization nit: replace occurrences of

  (high_bits << PyLong_SHIFT) + low_bits with
  (high_bits << PyLong_SHIFT) | low_bits
in Objects/longobject.c.  Motivation:
 - shouldn't unnecessarily mix bit ops with arithmetic ops (style)
 - this pattern should be spelt the same way thoughout (consistency)
 - it's very very very slightly faster: no need to worry about
   carries to the high digit (nano-optimization).

Objects/longobject.c

@@ -251,7 +251,7 @@ PyLong_AsLong(PyObject *vv)
 	}
 	while (--i >= 0) {
 		prev = x;
-		x = (x << PyLong_SHIFT) + v->ob_digit[i];
+		x = (x << PyLong_SHIFT) | v->ob_digit[i];
 		if ((x >> PyLong_SHIFT) != prev)
 			goto overflow;
 	}
@@ -296,7 +296,7 @@ PyLong_AsSsize_t(PyObject *vv) {
 	}
 	while (--i >= 0) {
 		prev = x;
-		x = (x << PyLong_SHIFT) + v->ob_digit[i];
+		x = (x << PyLong_SHIFT) | v->ob_digit[i];
 		if ((x >> PyLong_SHIFT) != prev)
 			goto overflow;
 	}
@@ -350,7 +350,7 @@ PyLong_AsUnsignedLong(PyObject *vv)
 	}
 	while (--i >= 0) {
 		prev = x;
-		x = (x << PyLong_SHIFT) + v->ob_digit[i];
+		x = (x << PyLong_SHIFT) | v->ob_digit[i];
 		if ((x >> PyLong_SHIFT) != prev) {
 			PyErr_SetString(PyExc_OverflowError,
 				"long int too large to convert");
@@ -386,7 +386,7 @@ PyLong_AsUnsignedLongMask(PyObject *vv)
 		i = -i;
 	}
 	while (--i >= 0) {
-		x = (x << PyLong_SHIFT) + v->ob_digit[i];
+		x = (x << PyLong_SHIFT) | v->ob_digit[i];
 	}
 	return x * sign;
 }
@@ -1170,7 +1170,7 @@ PyLong_AsUnsignedLongLongMask(PyObject *vv)
 		i = -i;
 	}
 	while (--i >= 0) {
-		x = (x << PyLong_SHIFT) + v->ob_digit[i];
+		x = (x << PyLong_SHIFT) | v->ob_digit[i];
 	}
 	return x * sign;
 }
@@ -1336,7 +1336,7 @@ inplace_divrem1(digit *pout, digit *pin, Py_ssize_t size, digit n)
 	pout += size;
 	while (--size >= 0) {
 		digit hi;
-		rem = (rem << PyLong_SHIFT) + *--pin;
+		rem = (rem << PyLong_SHIFT) | *--pin;
 		*--pout = hi = (digit)(rem / n);
 		rem -= (twodigits)hi * n;
 	}