tar: fix current_block confusion

Problem reported by Robert Morris in:
https://lists.gnu.org/r/bug-tar/2024-03/msg00001.html
* src/delete.c (flush_file): Simply return at EOF,
so that current_block continues to point to end of input.

src/delete.c

@@ -149,7 +149,7 @@ flush_file (void)
       flush_archive ();
       if (record_end == current_block)
 	/* Hit EOF */
-	break;
+	return;
     }
   current_block += blocks_to_skip;
 }