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.

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

MFtbemd:

Use MACHINE_CPUARCH in preference to MACHINE_ARCH. The former is the
source code location of the machine, the latter the binary output. In
general, we want to use MACHINE_CPUARCH instead of MACHINE_ARCH unless
we're tesitng for a specific target. The isn't even moot for
i386/amd64 where there's momemntum towards a MACHINE_CPUARCH == x86,
although a specific cleanup for that likely would be needed...

- Add ofw_bus_if.h to SRCS on sparc64 as envctrl.c and pcf_ebus.c depend
on it.
- Sync with sys/conf/files* and build pcf_isa.c only on i386 for now.
- Try to adhere to style.Makefile(5) (sorting, whitespace).

Finally complete some work on generalizing the PCF8584-based I2C
drivers I started quite some time before.

Retire the old i386-only pcf driver, and activate the new general
driver that has been sitting in the tree already for quite some
time.

Build the i2c modules for sparc64 architectures as well (where I've
been developing all this on).

Kill bogus isa compat opt file.

Major rework of the iicbus/smbus framework:

- VIA chipset SMBus controllers added
- alpm driver updated
- Support for dynamic modules added
- bktr FreeBSD smbus updated but not tested
- cleanup