FreeBSD_HEAD_amd64_gcc - Build #1345 - Fixed

FreeBSD_HEAD_amd64_gcc - Build #1345 - Fixed:

Build information: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_amd64_gcc/1345/
Full change log: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_amd64_gcc/1345/changes
Full build log: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_amd64_gcc/1345/console

Change summaries:

302369 by ngie:
Fix gcc warning

Remove -Wunused-but-set-variable (`mopt`).

Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D7119
MFC after: 1 week
X-MFC with: r302332
Reported by: Jenkins
Reviewed by: grehan (maintainer)
Sponsored by: EMC / Isilon Storage Division

302368 by ngie:
Fix gcc build errors with SSE 4.2 detection and gcc warnings

- Remove -Wunused-but-set-variable's (`len`, etc).
- Replace clang-specific tests in sse42_supported(..) with generic,
  FreeBSD-supported CPU feature tests, using macros and functions
  from machine/cpufunc.h and machine/specialreg.h . The previous method
  for determining SSE4.2 availability was only compatible with clang.
- Sort #includes per style(9).

Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D7119
MFC after: 1 week
X-MFC with: r302332
Reported by: Jenkins
Reviewed by: grehan (maintainer)
Sponsored by: EMC / Isilon Storage Division

302367 by ngie:
Fix gcc warnings

Remove unused function (`fifo_available`)

Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D7119
MFC after: 1 week
X-MFC with: r302332
Reported by: Jenkins
Reviewed by: grehan (maintainer)
Sponsored by: EMC / Isilon Storage Division

302366 by ngie:
Fix gcc warnings

- Put parentheses around bitwise OR'ed values in the `FIELD_COPY(..)` and
  `FIELD_REPLACE(..)` macros to mute warning from gcc 4.2.1.
- Remove -Wunused-but-set-variable's (`setup_addr`, `status_addr`).

Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D7119
MFC after: 1 week
X-MFC with: r302332
Reported by: Jenkins
Reviewed by: grehan (maintainer)
Sponsored by: EMC / Isilon Storage Division

302365 by ngie:
Fix gcc warnings

Remove -Wunused-but-set-variable (`error`). Cast calls with
`(void)` to note that the return value is explicitly ignored.

Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D7119
MFC after: 1 week
Reported by: Jenkins
Reviewed by: grehan (maintainer)
Sponsored by: EMC / Isilon Storage Division

302364 by ngie:
Fix gcc warnings

Add `WRAPPED_CTASSERT` macro by annotating CTASSERTs with __unused
to deal with -Wunused-local-typedefs warnings from gcc 4.8+.
All other compilers (clang, etc) use CTASSERT as-is. A more generic
solution for this issue will be proposed after ^/stable/11 is forked.

Consolidate all CTASSERTs under one block instead of inlining them in
functions.

Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D7119
MFC after: 1 week
Reported by: Jenkins
Reviewed by: grehan (maintainer)
Sponsored by: EMC / Isilon Storage Division

302363 by ngie:
Fix gcc warnings

Put cfl/prdt under AHCI_DEBUG #defines as they are only used in
those cases.

Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D7119
MFC after: 1 week
Reported by: Jenkins
Reviewed by: grehan (maintainer)
Sponsored by: EMC / Isilon Storage Division

302362 by ngie:
Fix gcc warnings

- Remove -Wunused-but-set-variable (newcpu)
- Always return VMEXIT_CONTINUE as the code always set retval to that value.

Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D7119
MFC after: 1 week
Reported by: Jenkins
Reviewed by: grehan (maintainer)
Sponsored by: EMC / Isilon Storage Division