* Finegrainify namespacification

* Finegrainify namespacification
* Add new constructors to allow insertion of terminator instructions at the
  end of basic blocks.
* Move a ReturnInst method out-of-line, so that the vtable and type info don't
  need to be emitted to every translation unit that uses the class.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10107 91177308-0d34-0410-b5e6-96231b3b80d8