is not relocated when freeing a compressed block.  This avoids the
costly rescan of the LRU list.  (Bug #35077, Issue #449)

At most one buffer-fix will be active at a time, affecting two blocks:
the buf_page_t and the compressed page frame. This should not block
the memory defragmentation in buf0buddy.c too much.  In fact, it may
avoid unnecessary copying if also prev_bpage belongs to the tablespace
that is being invalidated.

rb://240