Make mini-macro use AstBuilder or proc macros

[Manishearth]

We use the mini-macro crate to test how lints behave under macros.

It currently uses quasi quoting.

We should switch that to AstBuilder, or change it to a new-type procedural macro. I want to remove quote_*! from libsyntax and this is the only consumer.
rust-lang/rust#46849

(might fix this myself)

[Manishearth]

ideally we should just replace it with a single derive macro that triggers a lint