fix macro attribute feature-gate span

[pbkx]

Fixes #147135.

Issue #147135 reports a misleading feature-gate diagnostic for cross-crate macro_rules! macro attributes. This misleading feature-gate diagnostic causes rustc to point at the macro definition instead of user’s attribute call site.

My PR makes sure externally defined macro_rules! attributes are gated at the invocation span. Regression test verifies that the primary error points at the downstream #[foo::identity] attribute use

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r? @Kivooeo

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[Kivooeo]

I wonder if we also should add a check for this check below?

rust/compiler/rustc_expand/src/mbe/macro_rules.rs

Lines 773 to 776 in f28ac76

	if !features.macro_derive() {
	feature_err(sess, sym::macro_derive, span, "`macro_rules!` derives are unstable")
	.emit();
	}