qHash(QHostAddress) was added in Qt 5.0 (at least the version with uint seed = 0).
op==(QHostAddress::SpecialAddress, QHostAddress) was there since QHostAddress was
added before public history. Since QHostAddress does not have a \since, the I did
not supply one for op==, either.
Since the equality operator did not have unit-tests, added one.
Change-Id: I954a0df02464338f08a12ca58d4cc0ceb013e67a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>