Currently, CE_CACHE on strings is only used with opcache interned strings. This
patch extends usage to non-opcache interned strings as well. This means that
most type strings can now make use of CE_CACHE even if opcache is not loaded,
which allows us to remove TYPE_HAS_CE kind, and fix some discrepancies
depending on whether a type stores a resolved or non-resolved name.
There are two cases where CE_CACHE will not be used:
* When opcache is not used and a permanent interned string (that is not an
internal class name) is used as a type name during the request. In this case
we can't allocate a map_ptr index for the permanent string, as it would be
not be in the permanent map_ptr index space.
* When opcache is used but the script is not cached (e.g. eval'd code or
opcache full). If opcache is used, we can't allocate additional map_ptr
indexes at runtime, because they may conflict with indexes allocated by
opcache.
In these two cases we would end up not using CE caching for property types
(argument/return types still have the separate cache slot).
Nikita Popov