Two sparse fixes from Yuxuan Shui.

- Make "len" parameter of do_punch_hole an OFF_T.
- Clear sparse_past_write in sparse_end(), otherwise when write_sparse()
  is called for the next file, do_punch_hole() will be called with a pos
  that's not actually the current position in file, causing it to fail.

fileio.c

@@ -44,6 +44,8 @@ int sparse_end(int f, OFF_T size)
 {
 	int ret;
 
+	sparse_past_write = 0;
+
 	if (!sparse_seek)
 		return 0;
 

syscall.c

@@ -523,7 +523,7 @@ OFF_T do_fallocate(int fd, OFF_T offset, OFF_T length)
 
 /* Punch a hole at pos for len bytes. The current file position must be at pos and will be
  * changed to be at pos + len. */
-int do_punch_hole(int fd, UNUSED(OFF_T pos), int len)
+int do_punch_hole(int fd, UNUSED(OFF_T pos), OFF_T len)
 {
 #ifdef HAVE_FALLOCATE
 # ifdef HAVE_FALLOC_FL_PUNCH_HOLE