Fix the ManagedStatic list ordering when using DynamicLibrary::addPermanentLibrary.

Summary:
r295737 included a fix for leaking libraries loaded via. DynamicLibrary::addPermanentLibrary.
This created a problem where static constructors in a library could insert llvm::ManagedStatic objects before DynamicLibrary would register it's own ManagedStatic, meaning a crash could occur at shutdown.

r301562 exasperated this problem by cleaning up the DynamicLibrary ManagedStatic during llvm_shutdown.

Reviewers: v.g.vassilev, lhames, efriedma

Reviewed By: efriedma

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D33581

llvm-svn: 304027