X87: Flesh out vector ic state query and set mechanisms.

port c142994f742b52cd59aa15d0961d4b0034bcbf88

original commit message:

    Flesh out vector ic state query and set mechanisms.

    The IC system now fully integrates the vector concept and can
    handle loads and keyed loads vector-based.

BUG=

Review URL: https://codereview.chromium.org/763953002

Cr-Commit-Position: refs/heads/master@{#25556}