The use-case for `__is_same_uncvref` seems rather dubious, since not a
single use-cases needed the `remove_cvref_t` to be applied to both of
the arguments. Removing the alias makes it clearer what actually
happens, since we're not using an internal name anymore and it's clear
what the `remove_cvref_t` should apply to.
1f8e2a4b10