This sets the `get_tydesc()` return type correctly and removes the intrinsic module. See #3730, #3475.
Update: this now also removes the unused shape fields in tydescs.
the `test/run-pass/class-trait-bounded-param.rs` test was xfailed and
written in an ancient dialect of Rust so I've just removed it
this also removes `to_vec` from DList because it's provided by
`std::iter::to_vec`
an Iterator implementation is added for OptVec but some transitional
internal iterator methods are still left
To achieve this, the following changes were made:
* Move TyDesc, TyVisitor and Opaque to std::unstable::intrinsics
* Convert TyDesc, TyVisitor and Opaque to lang items instead of specially
handling the intrinsics module
* Removed TypeDesc, FreeGlue and get_type_desc() from sys
Fixes#3475.
I removed the `static-method-test.rs` test because it was heavily based
on `BaseIter` and there are plenty of other more complex uses of static
methods anyway.
