Make two QDT benchmarks data-driven and add more rows

The QDateTime benchmark's toMSecsSinceEpoch() and
toMSecsSinceEpochTz() each iterated the 2010s and had 1950 and 2050
variants for two other decades. I want to also test some earlier
decades and do similar for create(), so combine the existing triplets
as three rows of a data-driven test for each triplet, add the new rows
and apply the same to create().

In the process, turn an enum used for qint64 constants into a set of
constexpr qint64 declarations.

Pick-to: 6.4 6.3 6.2 5.15
Task-number: QTBUG-104012
Change-Id: I2657346b65d96a7ef7503cd33c870b688ea5dbff
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

0 files changed, 0 insertions, 0 deletions