swift234

BridgeObject: native object with no spare bits set

Naturally, the fast path for things like Array<Int> has to be that no
masking is required to get at the buffer.  Therefore, the state with no
spare bits set needs to be reserved for native objects.  After the
change, an ObjC non-tagged pointer is stored with all spare bits set, and
native objects are stored with 0..<N bits set, where N is the number of
spare bits.  ObjC tagged pointers are still stored verbatim.

Swift SVN r23430