geckolib: reupdate bindings to allow easy union modifications
geckolib: reupdate bindings to allow easy union modifications

This commit updates the current bindings with a m-c trunk build.

This improves quite a few things:
 * It adds `Debug` support for structs, which should be easy.
 * It generates unnamed structs definitions.
 * And... It allows changing union types directly!

The way mutating a union works is as follows. Each union field has an
unsized field of type `__BindgenUnionField<T>`, where `T` is the type of
the field.

The field has two unsafe methods, `as_ref` and `as_mut`, that would work
as follows (assuming 64 bit pointers):

````
let u = nsStyleUnion {
    mInt: Default::default(),
    mFloat: Default::default(),
    mPointer: Default::default(),
    _bindgen_data_: 0,
};

unsafe {
    assert_eq!(*u.mInt.as_ref() == 0);
    *u.mPointer.as_mut() = !0 as *mut _;
    assert_eq!(*u.mInt.as_ref() == !0);
    *u.mInt.as_mut() = 0;
    assert_eq!(*u.mInt.as_ref() == 0);
    assert_eq!(*u.mPointer.as_ref() == (!0 << 32) as *mut _);
}
```

peterjoel/servo,saneyuki/servo,mbrubeck/servo,emilio/servo,KiChjang/servo,pyfisch/servo,fiji-flo/servo,emilio/servo,larsbergstrom/servo,anthgur/servo,mattnenterprise/servo,szeged/servo,cbrewster/servo,nrc/servo,avadacatavra/servo,canaltinova/servo,mbrubeck/servo,nrc/servo,cbrewster/servo,KiChjang/servo,fiji-flo/servo,pyfisch/servo,splav/servo,eddyb/servo,peterjoel/servo,peterjoel/servo,avadacatavra/servo,paulrouget/servo,sadmansk/servo,jimberlage/servo,saneyuki/servo,fiji-flo/servo,rnestler/servo,SimonSapin/servo,paulrouget/servo,szeged/servo,steveklabnik/servo,ConnorGBrewster/servo,ConnorGBrewster/servo,jimberlage/servo,nnethercote/servo,avadacatavra/servo,paulrouget/servo,szeged/servo,mattnenterprise/servo,mattnenterprise/servo,KiChjang/servo,peterjoel/servo,mattnenterprise/servo,ConnorGBrewster/servo,larsbergstrom/servo,canaltinova/servo,CJ8664/servo,steveklabnik/servo,upsuper/servo,mbrubeck/servo,dsandeephegde/servo,ConnorGBrewster/servo,thiagopnts/servo,fiji-flo/servo,peterjoel/servo,dsandeephegde/servo,thiagopnts/servo,anthgur/servo,dati91/servo,nnethercote/servo,szeged/servo,saneyuki/servo,DominoTree/servo,rnestler/servo,dati91/servo,saneyuki/servo,paulrouget/servo,peterjoel/servo,peterjoel/servo,nrc/servo,notriddle/servo,KiChjang/servo,peterjoel/servo,DominoTree/servo,larsbergstrom/servo,thiagopnts/servo,dsandeephegde/servo,splav/servo,saneyuki/servo,larsbergstrom/servo,SimonSapin/servo,nnethercote/servo,eddyb/servo,DominoTree/servo,emilio/servo,DominoTree/servo,steveklabnik/servo,thiagopnts/servo,notriddle/servo,cbrewster/servo,avadacatavra/servo,nrc/servo,emilio/servo,nrc/servo,upsuper/servo,larsbergstrom/servo,larsbergstrom/servo,notriddle/servo,splav/servo,thiagopnts/servo,emilio/servo,eddyb/servo,emilio/servo,nrc/servo,paulrouget/servo,jimberlage/servo,larsbergstrom/servo,CJ8664/servo,anthgur/servo,paulrouget/servo,rnestler/servo,thiagopnts/servo,anthgur/servo,paulrouget/servo,mattnenterprise/servo,CJ8664/servo,jimberlage/servo,rnestler/servo,emilio/servo,sadmansk/servo,dsandeephegde/servo,paulrouget/servo,sadmansk/servo,jimberlage/servo,eddyb/servo,peterjoel/servo,pyfisch/servo,dati91/servo,fiji-flo/servo,cbrewster/servo,CJ8664/servo,steveklabnik/servo,sadmansk/servo,canaltinova/servo,SimonSapin/servo,anthgur/servo,KiChjang/servo,SimonSapin/servo,KiChjang/servo,avadacatavra/servo,notriddle/servo,ConnorGBrewster/servo,cbrewster/servo,CJ8664/servo,saneyuki/servo,KiChjang/servo,szeged/servo,szeged/servo,ConnorGBrewster/servo,pyfisch/servo,thiagopnts/servo,pyfisch/servo,KiChjang/servo,splav/servo,szeged/servo,dsandeephegde/servo,anthgur/servo,larsbergstrom/servo,upsuper/servo,rnestler/servo,splav/servo,mbrubeck/servo,dati91/servo,anthgur/servo,KiChjang/servo,eddyb/servo,splav/servo,jimberlage/servo,avadacatavra/servo,notriddle/servo,szeged/servo,canaltinova/servo,fiji-flo/servo,nrc/servo,rnestler/servo,saneyuki/servo,splav/servo,sadmansk/servo,paulrouget/servo,fiji-flo/servo,dati91/servo,paulrouget/servo,mattnenterprise/servo,DominoTree/servo,DominoTree/servo,DominoTree/servo,upsuper/servo,CJ8664/servo,dati91/servo,notriddle/servo,dsandeephegde/servo,nnethercote/servo,upsuper/servo,SimonSapin/servo,splav/servo,splav/servo,nnethercote/servo,nnethercote/servo,szeged/servo,DominoTree/servo,dati91/servo,szeged/servo,pyfisch/servo,saneyuki/servo,pyfisch/servo,notriddle/servo,steveklabnik/servo,cbrewster/servo,fiji-flo/servo,sadmansk/servo,jimberlage/servo,saneyuki/servo,emilio/servo,mbrubeck/servo,notriddle/servo,DominoTree/servo,anthgur/servo,jimberlage/servo,steveklabnik/servo,SimonSapin/servo,steveklabnik/servo,larsbergstrom/servo,SimonSapin/servo,notriddle/servo,nnethercote/servo,canaltinova/servo,eddyb/servo,ConnorGBrewster/servo,CJ8664/servo,larsbergstrom/servo,pyfisch/servo,sadmansk/servo,upsuper/servo,dsandeephegde/servo,eddyb/servo,rnestler/servo,canaltinova/servo,canaltinova/servo,CJ8664/servo,pyfisch/servo,SimonSapin/servo,mattnenterprise/servo,nnethercote/servo,dsandeephegde/servo,cbrewster/servo,mattnenterprise/servo,sadmansk/servo,nnethercote/servo,emilio/servo,mbrubeck/servo,mbrubeck/servo,peterjoel/servo,pyfisch/servo,splav/servo,jimberlage/servo,notriddle/servo,emilio/servo,dati91/servo,saneyuki/servo,cbrewster/servo,DominoTree/servo,thiagopnts/servo,eddyb/servo,ConnorGBrewster/servo,upsuper/servo,KiChjang/servo,nnethercote/servo,avadacatavra/servo,upsuper/servo,canaltinova/servo,avadacatavra/servo,rnestler/servo,mbrubeck/servo