Use exists instead of filter + match on []

[forki]

No description provided.

[smoothdeveloper]

would we prefer this style:

// Throw away null constraints if they are implied 
let hasTypesWithNullConstraint =
    others 
    |> List.exists (
        function
        | (TyparConstraint.SupportsNull(_)) -> not (TypeSatisfiesNullConstraint cenv.g m cxty) 
        | _ -> true
    ) 
if hasTypesWithNullConstraint 
then None
else Some cxty

I know most of the compiler has long lines, but from my perspective it really ease the flow of reading when we adopt shorter lines / expressions, introducing / naming a variable also helps

[dsyme]

@smoothdeveloper Per CONTRIBUTING,md, that sort of thing would be a separate cleanup PR (though it's fair to say that reducing line length isn't really a cleanup aim at the moment)

[dsyme]

This is very simple, merging now