Revert "Optimize QJsonObject::operator=="

This reverts commit 862fa24179,
which attempted to optimize QJsonObject::operator== under the
assumption that the entries it holds are lexicographically
sorted. They should be, because Object::indexOf() finds them
by binary search, but apparently both fromJson(), as well as
construction through op[] leave (some) entries unsorted.

This behavior should be fixed, because other code relies on
sorted entries, too, but until the problem is more fully under-
stood, revert the patch to unbreak equality comparisons.

Task-number: QTBUG-56843
Change-Id: I5b608c16d1bbcb4f01b75ce93bd58b49ff050be2
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

src/corelib/json/qjson_p.h

@@ -691,8 +691,6 @@ public:
     bool operator >=(const Entry &other) const;
 };
 
-inline bool operator!=(const Entry &lhs, const Entry &rhs) { return !(lhs == rhs); }
-
 inline bool Entry::operator >=(const QString &key) const
 {
     if (value.latinKey)

src/corelib/json/qjsonobject.cpp

@@ -545,8 +545,8 @@ bool QJsonObject::operator==(const QJsonObject &other) const
 
     for (uint i = 0; i < o->length; ++i) {
         QJsonPrivate::Entry *e = o->entryAt(i);
-        QJsonPrivate::Entry *oe = other.o->entryAt(i);
-        if (*e != *oe || QJsonValue(d, o, e->value) != QJsonValue(other.d, other.o, oe->value))
+        QJsonValue v(d, o, e->value);
+        if (other.value(e->key()) != v)
             return false;
     }