Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r228980:

Reapply r228785 now it has been tested by Adrian. Also add comments
with the old AR_SCR_SLE_XXX values, with a short explanation why they
were changed.

Reviewed by: adrian

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Replace Id keyword with FreeBSD keyword and set the svn props correctly.
No functional change.

add FreeBSD property

import ath hal

virgin import of ath hal