Remove final IWYU hints

IWYU is not a tool we have seen results from in some time.  I very much
suspect that these few comments are not enough to get a clean build.

Clean them up.  If we want to turn this tool back on in the future,
this patch can be reverted.

Tested: Comment only change.  Review only.

Change-Id: I45ff737800f9d8b1b63db2f482e59f815d7126a2
Signed-off-by: Ed Tanous <ed@tanous.net>