librustc: Fixed PNaCl linking!

I had to add 4 passes to the post-lto set. The first one, -resolve-aliases,
is needed to resolve some external functions in libc++. The rest are to clean up
issues exposed now that Rust crates no longer have external deps (with
-verify-pnaclabi-module passing).

Even with all the changes I've made trying to combat compile times, one-liners
still clock in at about 30 seconds. With 1500 run-pass tests @ 30s per test,
that'll clock in at about 75 minutes on a single core. Still ain't great, but at
least it won't take longer than overnight to complete. Note that as of this
commit not all tests pass; I've got some LLVM transform pass debugging to do.