squash outer pointer of Late-Closure-Classes

During UnCurry, closureConversionModern() lowers a Function node into
a Block of the form:

    {
      def hoisted(x_1: T_1, ..., x_N: T_n): R = body

       ScalaRunTime.lccMethodDisguiser(
         hoisted(zeroes-for-params-above)
       ).asInstanceOf[AbstractFunctionN[T_1, .., T_N, R]]
    }

The "hoisted" method becomes a bytecode-level instance-method,
unless the class declaring it is an implementation-class derived
from a trait (in which case "hoisted" becomes
a bytecode-level static method).

An instance "hoisted" method usually implies that an outer-pointer
is required by the anon-closure-class (unless the class declaring
the "hoisted method" is a Scala-level static module, in which case
the anon-closure knows how to grab the correct instance via
GETSTATIC MODULE$ thus doing without an outer-pointer)

Oftentimes an instance "hoisted method" actually does not depend
on THIS, or depends only on lifted-methods (thus not part of
the public API) which themselves exhibit such property (not depend
on THIS or depend only on methods that don't actually require THIS).

In class LCCOuterSquasher, method squashOuterForLCC() detects
the largest subset of "hoisted methods" (aka endpoints)
that can be made static, under the constraint that only
lifted-methods can be made static. This constraint amounts
to leaving the public API unchanged.

Once that subset has been determined, all usages of those
"must-be-made-static" methods are found, and rewritten as appropriate.

Finally, each Late-Closure-Class amenable to this transformation
is refactored:
  - its $outer field is removed,
  - its constructor is adapted removing the param for outer-pointer.

Compiler flag -Ylog:jvm informs which anon-closures have
their outer-pointer squashed.