Fix page_cache leak in cache_resize

Signed-off-by: Orit Wasserman <owasserm@redhat.com>

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Juan Quintela <quintela@redhat.com>
(cherry picked from commit 0db65d624e0211a43c011579d6607a50d8f06082)
Fix cache_resize to keep old entry age

Instead of using cache_insert do the update itself

Signed-off-by: Orit Wasserman <owasserm@redhat.com>

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Juan Quintela <quintela@redhat.com>
(cherry picked from commit a0ee2031dbf5f0183412d4b20a30cbfd404616a8)
page_cache: fix memory leak

XBZRLE encoded migration introduced a MRU page cache
meachnism. Unfortunately, cached items where never freed in
case of a collision in the page cache on cache_insert().

This lead to out of memory conditions during XBZRLE migration
if the page cache was small and there where a lot of collisions
in the cache.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Orit Wasserman <owasserm@redhat.com>

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Juan Quintela <quintela@redhat.com>
(cherry picked from commit 32a1c08b60a8ac0e63b54a5793a26b5e32b36618)
page_cache: dup memory on insert

The page cache frees all data on finish, on resize and
if there is collision on insert. So it should be the caches
responsibility to dup the data that is stored in the cache.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Orit Wasserman <owasserm@redhat.com>

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Juan Quintela <quintela@redhat.com>
(cherry picked from commit ee0b44aa9d9450e873a761ca2030b2fa3ec52eb0)