std personality _Unwind_Action should not be a enum

[Noratrieb]

The personality function takes an _Unwind_Action as an argument.

rust/library/std/src/sys/personality/gcc.rs

Lines 208 to 211 in d497e43

	unsafe extern "C" fn rust_eh_personality_impl(
	version: c_int,
	actions: uw::_Unwind_Action,
	_exception_class: uw::_Unwind_Exception_Class,

This is declared in the unwind crate as an enum

rust/library/unwind/src/unwinding.rs

Lines 5 to 13 in d497e43

	#[repr(C)]
	#[derive(Copy, Clone, PartialEq)]
	pub enum _Unwind_Action {
	_UA_SEARCH_PHASE = 1,
	_UA_CLEANUP_PHASE = 2,
	_UA_HANDLER_FRAME = 4,
	_UA_FORCE_UNWIND = 8,
	_UA_END_OF_STACK = 16,
	}

But in reality, this is actually bit flags:

Indicates what processing the personality routine is expected to perform, as a bit
mask. The possible actions are described below.

(from https://gitlab.com/x86-psABIs/x86-64-ABI 6.2.6)

This means that invalid values are being passed to this function, which is undefined behavior (since the only valid values for an enum are its exact variants).

(found by @pitust)