Protect against infinite macro expansion in def collector
Protect against infinite macro expansion in def collector

There was a test for this, but it wasn't actually working because the first
recursive expansion failed. (The comma...)

Even with this limit, that test (when fixed) still takes some time to pass
because of the exponential growth of the expansions, so I disabled it and added
a different one without growth.

rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer