Revert of [x64] Improve instruction selection for TruncateInt64ToInt32. (patchset #1 id:1 of https://codereview.chromium.org/936323004/)

Reason for revert:
Breaks SQLite

Original issue's description:
> [x64] Improve instruction selection for TruncateInt64ToInt32.
>
> R=svenpanne@chromium.org
>
> Committed: https://crrev.com/64a2717529e2197f3a789adabf86ca36f5eb764c
> Cr-Commit-Position: refs/heads/master@{#26739}

TBR=svenpanne@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/928723003

Cr-Commit-Position: refs/heads/master@{#26791}