SI-8143 Regressions with override checks, private members

These regressed in e609f1f20b, which excluded all private methods from
overriding checks. We should only exclude private[this] members on the
low end of a pair, as was done before that commit, and, we must also
exclude private members on the high side.

Why? Warning: reverse engineered intuition follows.

We need to report an error when if a private method in a subclass
has matches a less-private method in the super class and report an
error, lest the user be fooled into thinking it might be invoked
virtually. On the other hand, adding a private method to a super
class shouldn't invalidate the choice names of public members in
its superclasses.

I've removed the test case added by that commit and will lodge a
reworked version of it that Paul provided as a new issue. That shows
a bug with qualified private + inheritance.

In addition, the expectation of `neg/accesses.check` is reverted
to its 2.10.3 version, which I believe is correct. When it was
changed in e609f1f20b it sprouted a variation, `neg/accesses-2`,
which has now changed behaviour. The intent of that test will
be captured in the aforementioned issue covering qualified private
inheritance.
Prohibit views targeting AnyVal

Library changes in Scala 2.10 mean that we are left with the
unfortunate situation of admitting:

    scala> "": AnyVal
    res0: AnyVal =

 We already have explicit checks in place to prevent views
 targeting `AnyRef`. This commit balances this out by prohibiting
 `AnyVal`, as well.

The enclosed test shows that this case is now prevented. If multiple
implicits views are applicable, the ambiguity error is still raised;
these check comes right at the end. Maybe that ought to be changed,
but I don't think it matters too much.

I've also disabled this prohibition under -Xsource:2.10.
SI-8213 AnyRefMap.getOrElseUpdate is faulty

Altered getOrElseUpdate to be robust to the map changing out from under it as a result of calling the default value method.  Side-effects FTW!

Made a comparable change in LongMap also, as it was also affected.  And added a test to SetMapConsistencyTest.
Merge pull request #3416 from retronym/topic/any-val-implicit

Prohibit views targeting AnyVal
Merge pull request #3434 from Ichoran/issue/8213

SI-8213 AnyRefMap.getOrElseUpdate is faulty
SI-7700 @unspecialized, Part Deux: Now Working.

This annotation was introduced to allow us to mark methods within
a specialized trait as immune from specialization. In particular,
this is desirable for `Function1.{andThen, compose}`.

However, it seems we need to check for this in two places in the
specialization code base. The feature is now backed with a test.
Merge pull request #3357 from retronym/ticket/8143

SI-8143 Regressions with override checks, private members
Optimize the pickler phase

 - move "erroneous type" diagnostic into a crash recovery handler,
    rather than running it proactively
 - move the "unexpanded macros" check into refchecks.

 Cuts this phase in half, from about 1% of compile time to 0.5%.
Merge pull request #3425 from retronym/ticket/7700

SI-7700 @unspecialized, Part Deux: Now Working.
Merge pull request #3447 from retronym/topic/opt9

Optimize the pickler phase