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: r222656

Upgrade libcompiler_rt from revision 117047 to 132478.

It seems there have only been a small amount to the compiler-rt source
code in the mean time. I'd rather have the code in sync as much as
possible by the time we release 9.0. Changes:

- The libcompiler_rt library is now dual licensed under both the
University of Illinois "BSD-Like" license and the MIT license.

- Our local modifications for using .hidden instead of .private_extern
have been upstreamed, meaning our changes to lib/assembly.h can now be
reverted.

- A possible endless recursion in __modsi3() has been fixed.

- Support for ARM EABI has been added, but it has no effect on FreeBSD
(yet).

- The functions __udivmodsi4 and __divmodsi4 have been added.

Requested by: many, including bf@ and Pedro Giffuni

Upgrade libcompiler_rt to upstream revision 147390.

This version of libcompiler_rt adds support for __mulo[sdt]i4(), which
computes a multiply and its overflow flag. There are also a lot of
cleanup fixes to headers that don't really affect us.

Updating to this revision should make it a bit easier to contribute
changes back to the LLVM developers.

Import compiler-rt r147390.