Drop ambiguous operator overloads
Drop ambiguous operator overloads

Clang rightfully complained about the operator overloads being
ambiguous. Now the Simdize Reference wrapper only overloads operator
invocations with a second Reference wrapper.

Signed-off-by: Matthias Kretz <372ea4eca737a13cd010ee806d4ce7b98ee71550@kde.org>

chr-engwer/Vc,chr-engwer/Vc,VcDevel/Vc,chr-engwer/Vc,VcDevel/Vc,VcDevel/Vc,VcDevel/Vc