As of commit 7767cbb3b0,
the tests/ui/consts/const-eval/ub-int-array.rs test is
failing on big-endian platforms (in particular s390x),
as the stderr output contains a hex dump that depends
on endianness.
Since this point intentionally verifies the hex dump to
check the uninitialized byte markers, I think we should
not simply standardize away the hex dump as is done with
some of the other tests in this directory.
However, most of the test is already endian-independent.
The only exception is one line of hex dump, which can
also be made endian-independent by choosing appropriate
constants in the source code.
Since the 32bit and 64bit stderr outputs were already
(and remain) identical, I've merged them and removed
the stderr-per-bitwidth marker.
Fixes (again) https://github.com/rust-lang/rust/issues/105383.
