Higher-kinded F-bounded types are not recognized

[smarter]

This causes a stack overflow:

class Foo[A]
class Bar[CC[X] <: Foo[CC[X]]]

The reason why is explained in #943 (comment)

[smarter]

Reproduced with ./scala-scala/src/library/scala/collection/generic/MutableSortedSetFactory.scala

[odersky]

There are still two test failures in scala-collections-whitelist which are suspected instances of #974. @smarter can you take a look at them?