Amends 2e1763d83a.
The new range ctors need deduction guides, since the compiler can't
deduce the value_type from a pair of iterators.
Change-Id: I3ec1e5f91305b317c443b6a70246be416b55bad9
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
247ab241c7