ignore more type aliases in unnecessary_cast

Author: Centri3

tests/ui/unnecessary_cast.rs

@@ -69,7 +69,6 @@ fn main() {
     // do not lint cast from cfg-dependant type
     let x = 0 as std::ffi::c_ulong;
     let y = x as u64;
-    // this already isn't linted,
     let x: std::ffi::c_ulong = 0;
     let y = x as u64;