Ignore big-endian targets in UI tests with raw bytes

Some `const` UI tests have raw bytes in their output that are sensitive
to the target endianness. We could consider something like the directive
`stderr-per-bitwidth` for endian, but we only ever test little-endian in
CI, so that would likely bit rot. For now, just ignore big-endian.

Author: cuviper

src/test/ui/const-ptr/forbidden_slices.rs

@@ -1,3 +1,4 @@
+// ignore-endian-big
 // stderr-per-bitwidth
 // normalize-stderr-test "alloc[0-9]+" -> "ALLOC_ID"
 // normalize-stderr-test "a[0-9]+\+0x" -> "A_ID+0x"

src/test/ui/consts/const-eval/ub-enum.rs

@@ -1,3 +1,4 @@
+// ignore-endian-big
 // stderr-per-bitwidth
 #![feature(never_type)]
 #![allow(invalid_value)]

src/test/ui/consts/const-eval/ub-nonnull.rs

@@ -1,3 +1,4 @@
+// ignore-endian-big
 // stderr-per-bitwidth
 #![feature(rustc_attrs)]
 #![allow(const_err, invalid_value)] // make sure we cannot allow away the errors tested here

src/test/ui/consts/const-eval/ub-ref-ptr.rs

@@ -1,3 +1,4 @@
+// ignore-endian-big
 // ignore-tidy-linelength
 // stderr-per-bitwidth
 #![allow(invalid_value)]

src/test/ui/consts/const-eval/ub-uninhabit.rs

@@ -1,3 +1,4 @@
+// ignore-endian-big
 // stderr-per-bitwidth
 #![allow(const_err)] // make sure we cannot allow away the errors tested here
 

src/test/ui/consts/const-eval/ub-wide-ptr.rs

@@ -1,4 +1,5 @@
 // stderr-per-bitwidth
+// ignore-endian-big
 // ignore-tidy-linelength
 #![allow(unused)]
 

src/test/ui/consts/issue-83182.rs

@@ -1,3 +1,4 @@
+// ignore-endian-big
 // stderr-per-bitwidth
 
 use std::mem;

src/test/ui/consts/std/alloc.rs

@@ -1,5 +1,6 @@
 // stderr-per-bitwidth
 // ignore-debug (the debug assertions change the error)
+// ignore-endian-big
 use std::alloc::Layout;
 
 // ok

src/test/ui/consts/validate_never_arrays.rs

@@ -1,3 +1,4 @@
+// ignore-endian-big
 // stderr-per-bitwidth
 #![feature(never_type)]