Subzero: Remove the LEAHACK workarounds.

They are no longer needed now that we aren't using the buggy llvm-mc parser for Intel syntax.

This also gets all spec2k components to work with -build-on-read.

Also, adds an emit-time check that infinite-weight Variables actually got a physical register.

BUG= none
R=jvoung@chromium.org

Review URL: https://codereview.chromium.org/696153002
2 files changed