Rollup merge of #106045 - RalfJung:oom-nounwind-panic, r=Amanieu

default OOM handler: use non-unwinding panic, to match std handler

The OOM handler in std will by default abort. This adjusts the default in liballoc to do the same, using the `can_unwind` flag on the panic info to indicate a non-unwinding panic.

In practice this probably makes little difference since the liballoc default will only come into play in no-std situations where people write a custom panic handler, which most likely will not implement unwinding. But still, this seems more consistent.

Cc `@rust-lang/wg-allocators,` https://github.com/rust-lang/rust/issues/66741