adapt to ${CC_WNO_ADDRESS_OF_PACKED_MEMBER}

Simplify CWARNFLAGS to use ${CC_WNO_ADDRESS_OF_PACKED_MEMBER}
which works for both clang and gcc, and remove compiler-specific
equivalents.

bsd.own.mk: rename to CC_WNO_ADDRESS_OF_PACKED_MEMBER

Provide a single variable
CC_WNO_ADDRESS_OF_PACKED_MEMBER
with options for both clang and gcc, to replace
CLANG_NO_ADDR_OF_PACKED_MEMBER
CC_NO_ADDR_OF_PACKED_MEMBER
GCC_NO_ADDR_OF_PACKED_MEMBER

Using the convention CC_compilerflag, where compilerflag
is based on the full compiler flag name.

Refactor and rewrite of newfs_udf(8) and makefs(8) (-t udf) with a shared
section for fsck_udf(8).

Newfs_udf and makefs support predefined disc image profiles, harddisc
partitions (disklabel and wedges on all generic block devices) and all optical
media types on CD/DVD/BD writers.

Newfs_udf and makefs now also support formatting of UDF 2.50 with a metadata
partition.

add support for new GCC 9 warnings that may be too much to fix
right now. new address-of-packed-member and format-overflow
warnings have new GCC_NO_ADDR_OF_PACKED_MEMBER amd
GCC_NO_FORMAT_OVERFLOW variables to remove these warnings.

apply to a bunch of the tree. mostly, these are real bugs that
should be fixed, but in many cases, only by removing the 'packed'
attribute from some structure that doesn't really need it. (i
looked at many different ones, and while perhaps 60-80% were
already properly aligned, it wasn't clear to me that the uses
were always coming from sane data vs network alignment, so it
doesn't seem safe to remove packed without careful research for
each affect struct.) clang already warned (and was not erroring)
for many of these cases, but gcc picked up dozens more.

Disable a couple of warnings until further investigation.

branches: 1.5.8;
Merge riastradh-drm2 to HEAD.

Initial split up for making newfs_udf(8) routines suitable for makefs_udf(8)

branches: 1.3.6; 1.3.12; 1.3.16;
Enable WARNS=4 by default except for:
dump dump_lfs fsck_ffs fsck_lfs fsdb mount_smbfs
newfs_ext2fs newfs_lfs resize_lfs setkey

branches: 1.2.2;
Ensure that all the files in SRCS are *.c files (there were some
files matching *.o (!) in the list). Thanks to cube@ for spotting
what I could not see. Should fix issue with UPDATE builds across
the recent time_t merge and associated shared lib major bumps.

branches: 1.1.2; 1.1.4; 1.1.6;
Import writing part of the UDF file system making optical media like CD's
and DVD's behave like floppy discs. Writing is supported upto and including
version 2.01; version 2.50 and 2.60 will follow.

Also extending the UDF implementation to support symbolic links and
hardlinks.

Added are the mmcformat(8) tool to format rewritable CD/DVD discs and
newfs_udf(8).

Limitations:
all operations can be performed on the file system though the
sheduling is currently optimised for archiving workloads.

mv(1)/rename(2) is currently only implemented for non-directories.