FreeBSD_HEAD_amd64_gcc4.9 - Build #389 - Fixed

FreeBSD_HEAD_amd64_gcc4.9 - Build #389 - Fixed:

Build information: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_amd64_gcc4.9/389/
Full change log: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_amd64_gcc4.9/389/changes
Full build log: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_amd64_gcc4.9/389/console

Change summaries:

287265 by imp:
Remove now obsolete comment.

MFC After: 2 days

287264 by imp:
Per overwhelming sentiment in the code review, use FEATURE instead.

Differential Revision: https://reviews.freebsd.org/D3488
MFC After: 2 days

287263 by imp:
Comment out cleaning files, since it cleans too much.

287262 by imp:
Remove .WAIT hacks and put in specific dependencies.

287260 by imp:
Add missing ofw_machdep.h. Make x86 ofw_machdep.h work pc98 too.
This allows the owc module to compile on pc98 and seems preferable to
adding another special case in the build system.

287259 by pfg:
Add underscores to attributes when checking for __has_attribute.

This is a good practice to avoid confusion with allowed macros.

Suggested by:	jilles

287258 by andrew:
Move dwmmc.h to dwmmc_reg.h. This is in preperation for adding support to
subclass the dwmmc driver to allow SoC specific attachments.

Sponsored by:	ABT Systems Ltd

287257 by imp:
Add back missing -m32 for amd64 and powerpc64 that was lost
in the move to bsd.stand.mk.

287256 by trasz:
Fix an NFS server bug that manifested in "ls -al" displaying a plus
sign on every directory exported via NFSv4 with NFSv4 ACLs enabled.

Reviewed by:	rmacklem_at_
MFC after:	1 month
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D3502

287255 by pfg:
trailing space

287254 by pfg:
Be more GCC-friendly with attributes

Being clang the default compiler, we were always giving precedence to
the __has_attribute check. Unfortunately clang generally doesn't support
the new attributes (alloc_size was briefly supported and then reverted)
so we were always doing both checks. Give the precedence to GCC as that is
the working case now.

Do the same for  __has_builtin() for consistency.

287253 by imp:
Fix cleaning of files generated from .m sources.

287250 by andrew:
Only check for the bus frequency if it has not already been set, for
example through a driver running as a subclass of this.

Sponsored by:	ABT Systems Ltd