MFC r314651,r318439,r318440:

r314651:

sys/modules: normalize .CURDIR-relative paths to SRCTOP

This simplifies make output/logic

Tested with: `cd sys/modules; make ALL_MODULES=` on amd64

r318439:

Normalize .PATH on SRCTOP

This will help Jenkins dedupe 9 warnings between the static build and
the module build of ipsec(4).

Missed in SRCTOP conversion in r314651.

MFC with: r314651

r318440:

Normalize SYSDIR on SRCTOP instead of .CURDIR

This is being done to simplify pathing for CFLAGS and source files.

MFC r305393:

Make some additional -Wconstant-conversion warnings from clang 3.9.0 in
bwn(4) non-fatal for now.

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

bwn, bwn_pci, siba_bwn: add missing opt_*.h dependencies.

[bwn] add in bwn n-phy linking.

* The default kernel and options won't build the GPL PHY bits;
* bwn(4) defaults to building as a module anyway!;
* If BWN_GPL_PHY is specified in the config file, and you uncomment
the GPL PHY bits in the module Makefile, you'll get a working
N-PHY.

This is specifically designed to be obtuse for now, as I don't want
to flip it on by default. It's easy enough for people to flip on
and build, and it's a module so the default GENERIC kernel won't be
GPL tainted.

I'll have to add an actual HAL layer that allows the GPL PHY to be loaded
before if_bwn so it can be "magic", but that'll come later.

Tested:

* BCM4321 11abg NIC, STA mode

[bwn] add in the new phy common and utils files.

They're not yet used by included code; that'll come next.

[bwn] break out the 'g' phy code into a separate source file.

* Break out the 'g' phy code;
* Break out the debugging bits into a separate source file, since
some debugging prints are done in the phy code;
* Make some more chip methods in if_bwn.c public.

This brings the size of if_bwn.c down to 6,805 lines which is now
approaching managable.

[bwn] break out the LP PHY code into a separate file.

This (and eventually migrating the other PHY code out) is in preparation
for adding the 11n PHY. No, the 11ac PHY (for the BCM4260 softmac part) isn't
yet open source, so we can't grow that. Yet.

This trims ~3,700 lines of code from if_bwn.c, bringing it down to a slightly
less crazy sounding 10,446 lines of code.

Re-support CWARNFLAGS, lost when bsd.sys.mk was removed. Also, support
CWARNFALGS.$file centrally so we don't have to have it in all the
places. Remove a few warning flags that are no longer needed.
Also, always use -Wno-unknown-pragma to (hopefully temporarily) work
around #pragma ident in debug.h in the opensolaris code. Remove some
stale warning suppression that's no longer necessary.

Upgrade our copy of llvm/clang to trunk r162107. With thanks to
Benjamin Kramer and Joerg Sonnenberger for their input and fixes.

adds bwn(4) driver for supporting Broadcom BCM43xx chipsets.

o uses v4 firmware instead of v3. A port will be committed to create
the bwn firmware module.
o supports B/G and LP(low power) PHYs.
o supports 32 / 64 bits DMA operations.
o tested on big / little endian machines so should work on all
architectures.

It'd not connected to the build until the firmware port is committed.