Require SSA in vasm-fold-imms

Summary: Remove the workaround

Reviewed By: @alexmalyshev

Differential Revision: D1571744
Bumping `ProxyManager` version to a version that correctly handles HHVM's `Closure::bind()` support

Summary: Closes https://github.com/facebook/hhvm/pull/3824

Reviewed By: @fredemmott

Differential Revision: D1571955