remove trailing whitespaces in missing spans

[scampi]

Close #3423

[scampi]

Build failures are unrelated to the PR.

Clippy fails to compile:

error[E0433]: failed to resolve: could not find `item_path` in `ty`
   --> clippy_lints/src/utils/mod.rs:105:10
    |
105 | impl ty::item_path::ItemPathBuffer for AbsolutePathBuffer {
    |          ^^^^^^^^^ could not find `item_path` in `ty`
error[E0433]: failed to resolve: could not find `item_path` in `ty`
   --> clippy_lints/src/utils/mod.rs:106:33
    |
106 |     fn root_mode(&self) -> &ty::item_path::RootMode {
    |                                 ^^^^^^^^^ could not find `item_path` in `ty`
error[E0433]: failed to resolve: could not find `item_path` in `ty`
   --> clippy_lints/src/utils/mod.rs:107:30
    |
107 |         const ABSOLUTE: &ty::item_path::RootMode = &ty::item_path::RootMode::Absolute;
    |                              ^^^^^^^^^ could not find `item_path` in `ty`
error[E0433]: failed to resolve: could not find `item_path` in `ty`
   --> clippy_lints/src/utils/mod.rs:107:57
    |
107 |         const ABSOLUTE: &ty::item_path::RootMode = &ty::item_path::RootMode::Absolute;
    |                                                         ^^^^^^^^^ could not find `item_path` in `ty`
error: aborting due to 4 previous errors

and Cargo fails on a test which seems to have been occurring for a while rust-lang/cargo#6258.

[topecongiro]

Thanks!