Fix forward type family in boot file (9.8.2)

[alt-romes]

Fixes an hs-boot file which had an incorrect forward declaration of a closed type family. vulkan would successfully compile despite the hs-boot error with 9.8.1, but not with 9.8.2 because of bug fixes which makes the compiler now reject this invalid program.

We need to use the weird type family A x where .. (with two literal dots after where) to declare the type family in the boot file.

[alt-romes]

I realise now that these sources may be autogenerated.
Where could I do this change correctly @expipiplus1 ?

[k355l3r-5yndr0m3]

@alt-romes Reading the code, I think I found the line that need to change.

vulkan/generate-new/src/Render/Spec/Extends.hs

Lines 187 to 195 in 474ea9d

	class PeekChain (xs :: [Type])
	class PokeChain (xs :: [Type])
	type family Extends (p :: [Type] -> Type) (x :: Type) :: Constraint
	type family Extendss (p :: [Type] -> Type) (xs :: [Type]) :: Constraint where
	Extendss p '[] = ()
	Extendss p (x : xs) = (Extends p x, Extendss p xs)
	type family Chain (xs :: [a]) = (r :: a) | r -> xs where
	Chain '[] = ()
	Chain (x:xs) = (x, Chain xs)

[alt-romes]

@dpwiz I've updated this patch to change the bindings generation code. The CI failures look unrelated to this patch.