QVariant::fromValue: Add rvalue optimization

When passing an rvalue-reference to QVariant, there is no reason to make
a copy if the type is moveable. Moreover, we know that the pointer which
we construct from the object passed to fromValue non-null. We make use
of both facts by parametrizing custom_construct on
non-nullness and availability of a move-ctor, and then dispatching to
the suitable template.
We need to keep the const T& overload, as otherwise code which
explicitly specializes fromValue and passes a const lvalue to it would
stop to compile.

[ChangeLog][QtCore][QVariant] Added fromValue() overload taking rvalues.

Change-Id: I44fb757d516ef364fe7967bc103b3f98278b4919
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

0 files changed, 0 insertions, 0 deletions