Rollup merge of rust-lang#101339 - the8472:ci-randomize-debug, r=Mark-Simulacrum

enable -Zrandomize-layout in debug CI builds

This builds rustc/libs/tools with `-Zrandomize-layout` on *-debug CI runners.

Only a handful of tests and asserts break with that enabled, which is promising. One test was fixable, the rest is dealt with by disabling them through new cargo features or compiletest directives.

The config.toml flag `rust.randomize-layout` defaults to false, so it has to be explicitly enabled for now.

Author: matthiaskrgr

Diff for: alloc/Cargo.toml

@@ -52,4 +52,5 @@ check-cfg = [
     'cfg(no_global_oom_handling)',
     'cfg(no_rc)',
     'cfg(no_sync)',
+    'cfg(randomized_layouts)',
 ]

Diff for: alloc/src/collections/btree/node/tests.rs

@@ -90,7 +90,7 @@ fn test_partial_eq() {
 
 #[test]
 #[cfg(target_arch = "x86_64")]
-#[cfg_attr(miri, ignore)] // We'd like to run Miri with layout randomization
+#[cfg_attr(any(miri, randomized_layouts), ignore)] // We'd like to run Miri with layout randomization
 fn test_sizes() {
     assert_eq!(core::mem::size_of::<LeafNode<(), ()>>(), 16);
     assert_eq!(core::mem::size_of::<LeafNode<i64, i64>>(), 16 + CAPACITY * 2 * 8);