Fix ICEs in gcc 4.6.3 for small-int typed_flags.

Subtle failures in nested template instantiations there, for
sal_{u}Int8 and sal_{u}Int16 - use wide-int fallback to do bitmask
ops. Type is not used to store any dynamic values.

This partially reverts a1ecce3a

Change-Id: Ifa7070c1c3830fd70d7ced082d651411ff523444