#78086 provided the trait we want to use for this: `__libcpp_integer`. In some `libcxx/containers/views/mdspan` tests, improper uses of `char` are replaced with `signed char`. Fixes #73715
#78086 provided the trait we want to use for this: `__libcpp_integer`. In some `libcxx/containers/views/mdspan` tests, improper uses of `char` are replaced with `signed char`. Fixes #73715