bind + argc specialization = 20x perf boost

Default logic of mirror construction, which gets triggered via
reflectField/reflectMethod/reflectConstructor, validates a lot of facts
about its arguments.

This takes quite a bit of time, which significantly degrades performance
of reflection-heavy applications. Proposed two changes provide an order
of magnitude performance boost to a simple app, which repeatedly invokes
the same method for different receiver instances.
a few performance improvements for toArray

First of all the typo I have made when migrating from manifests to tags.
`repr.getClass` in `WrappedArray` should read `array.getClass`.

Secondly manifests for Any, Object/AnyRef, AnyVal, Null and Nothing
now have their `newArray` methods overridden to avoid reflective overhead
of array instantiation.
Merge pull request #1821 from scalamacros/ticket/6638

bind + argc specialization = 20x perf boost