Fix ordering of PassExtension registry and LibraryHandles registry construction
Because PassExtension registry (may) hold reference to function obtained through
dlsym, it must be constructed *after* the libraryHandles. To enforce that order, the ManagedStatic holding the library handles is dereferenced (hence constructed) before each call ro the PassExtension registry.
This effectively fixes llvm/test/Feature/load_extension.ll that exhibit the
problem when Polly is linked statically within LLVM.