implement the rest of the language features in the self-hosted x86 backend

[andrewrk]

zig/src/target.zig

Lines 597 to 615 in 085cc54

	.error_return_trace => switch (backend) {
	.stage2_llvm => true,
	else => false,
	},
	.is_named_enum_value => switch (backend) {
	.stage2_llvm => true,
	else => false,
	},
	.error_set_has_value => switch (backend) {
	.stage2_llvm, .stage2_wasm => true,
	else => false,
	},
	.field_reordering => switch (backend) {
	.stage2_c, .stage2_llvm => true,
	else => false,
	},
	.safety_checked_instructions => switch (backend) {
	.stage2_llvm => true,
	else => false,

• error_return_trace compiler: include error trace in all functions, implement for x86_64 backend #22572
• is_named_enum_value x86_64: implement error set and enum safety #22876
• error_set_has_value x86_64: implement error set and enum safety #22876
• field_reordering x86_64: enable struct field reordering #22521
• safety_checked_instructions x86_64: implement safety checked instructions #22908
• panic_fn self-hosted x86 backend has formatted panics disabled #21529
• all_vector_instructions x86_64: implement conversions between float and int vectors #22873

[mlugg]

safety_checked_instructions need not block #22257, because Sema has fallbacks (lowering the safety checks itself) which are used when this feature is unsupported.