`trivial_bounds` lint lints on non-global associated type constraints

#![feature(trivial_bounds)]

trait Trait {
    type Assoc;
}
impl<T> Trait for T {
    type Assoc = T;
}

fn foo<T>()
where
    u32: Trait<Assoc = T>,
{
}

this results in

warning: trait bound u32: Trait does not depend on any type or lifetime parameters
  --> <source>:12:10
   |
12 |     u32: Trait<Assoc = T>,
   |          ^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(trivial_bounds)]` on by default

but should not, as the corresponding projection bound does reference a generic parameter (and requires this function to only be called with T = u32.

Start by compiling the standalone Rust example with #![feature(trivial_bounds)] and confirm the warning on the associated type constraint. Then trace the trivial_bounds lint handling for projection bounds. Done means this generic-dependent constraint no longer produces the warning while the lint still reports genuinely non-generic bounds.