patch 9.2.0337: list indexing broken on big-endian 32-bit platforms

Problem:  check_range_index_one() expects a long * but n1 is a
          varnumber_T. Casting varnumber_T * to long * is undefined
          behaviour and reads the wrong bytes on big-endian platforms
          (John Paul Adrian Glaubitz)
Solution: Use a local long variable and pass that pointer to
          check_range_index_one() (James McCoy)

fixes:  #19798
closes: #19952

Signed-off-by: James McCoy <jamessan@jamessan.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/list.c

@@ -1368,7 +1368,8 @@ list_slice_or_index(
     {
 	// copy the item to "var1" to avoid that freeing the list makes it
 	// invalid.
-	listitem_T *li = check_range_index_one(list, (long *)&n1, TRUE, TRUE);
+	long index = n1;
+	listitem_T *li = check_range_index_one(list, &index, TRUE, TRUE);
 	if (li == NULL)
 	    return FAIL;
 	copy_tv(&li->li_tv, &var1);

src/version.c

@@ -734,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    337,
 /**/
     336,
 /**/