The topmost bit in the class field isn't a "cache flush" flag in mDNS

The topmost bit in the class field isn't a "cache flush" flag in mDNS
queries.  Display that bit correctly (as per Marc Krochmal's request).

In mDNS, the topmost bit of the class field should be handled the same
way regardless of the value of the lower 15 bits, and *vice versa* -
they're independent fields.