Remove two unused static methods of QDateTimePrivate

... along with the two matching unused methods of QDateTime's test.

Change-Id: Id11a4b1b0132587f0df451d49c0043e9425d87ad
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/tools/qdatetime_p.h

@@ -140,9 +140,6 @@ public:
     // Inlined for its one caller in qdatetime.cpp
     inline void setUtcOffsetByTZ(qint64 atMSecsSinceEpoch);
 #endif // timezone
-
-    static inline qint64 minJd() { return QDate::minJd(); }
-    static inline qint64 maxJd() { return QDate::maxJd(); }
 };
 
 QT_END_NAMESPACE

tests/auto/corelib/tools/qdatetime/tst_qdatetime.cpp

@@ -155,8 +155,6 @@ private:
     QDateTime invalidDateTime() const { return QDateTime(invalidDate(), invalidTime()); }
     QDate invalidDate() const { return QDate(); }
     QTime invalidTime() const { return QTime(-1, -1, -1); }
-    qint64 minJd() const { return QDateTimePrivate::minJd(); }
-    qint64 maxJd() const { return QDateTimePrivate::maxJd(); }
 };
 
 Q_DECLARE_METATYPE(Qt::TimeSpec)