QHostAddress: add missing docs

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>

src/network/kernel/qhostaddress.cpp

@@ -1251,6 +1251,11 @@ QDebug operator<<(QDebug d, const QHostAddress &address)
 }
 #endif
 
+/*!
+    \since 5.0
+    \relates QHostAddress
+    Returns a hash of the host address \a key, using \a seed to seed the calculation.
+*/
 uint qHash(const QHostAddress &key, uint seed)
 {
     // both lines might throw
@@ -1258,6 +1263,15 @@ uint qHash(const QHostAddress &key, uint seed)
     return qHashBits(key.d->a6.c, 16, seed);
 }
 
+/*!
+    \relates QHostAddress
+    \fn operator==(QHostAddress::SpecialAddress lhs, const QHostAddress &rhs)
+
+    Returns \c true if special address \a lhs is the same as host address \a rhs;
+    otherwise returns \c false.
+
+    \sa isEqual()
+*/
 #ifndef QT_NO_DATASTREAM
 
 /*! \relates QHostAddress

tests/auto/network/kernel/qhostaddress/tst_qhostaddress.cpp

@@ -271,6 +271,7 @@ void tst_QHostAddress::specialAddresses()
     //check special address equal to itself (QTBUG-22898), note two overloads of operator==
     QVERIFY(QHostAddress(address) == QHostAddress(address));
     QVERIFY(QHostAddress(address) == address);
+    QVERIFY(address == QHostAddress(address));
     QVERIFY(!(QHostAddress(address) != QHostAddress(address)));
     QVERIFY(!(QHostAddress(address) != address));