The default value of the $format parameter of the APCIterator constructur is
APC_ITER_ALL which instructs the iterator to provide all available information
on cache values being iterated over. Only the key value is necessary for
matching and deletion via apc_delete(), though.

This prevents a "Format values FILENAME, DEVICE, INODE, MD5, NUM_HITS, MTIME,
CTIME, DTIME, ATIME, REFCOUNT not supported yet." notice on HHVM.

One of the other failures is no running server.

Sometimes it's not possible to disable APC entirely and some of
apc_functions are disabled. Only thing which is possible is
to disable apc.enable option.

see http://www.php.net/manual/en/apciterator.construct.php

This is possible because it is possible to only use xcache as an opcode cache
but not a variable cache.

Conflicts:
	lib/private/vcategories.php