Fix incorrect gating of nonterminals in key-value attributes

Fixes #85432

When processing a `#[derive]` or `#[cfg_eval]` attribute, we need to
re-parse our attribute target, which requires flattenting all
`Nonterminals`. However, this caused us to incorrectly gate on a
(flattented) nonterminal in a key-value attribute, which is supposed to
be allowed.

Since we already perform this gating during the initial parse, we
suppress it in `capture_cfg` mode.

0 files changed, 0 insertions, 0 deletions