branches: 1.9.20;
Add INSTALL_SMALL here as well, otherwise we break the build. Thanks to
he for catching this.

- whitespace consistency cleanup
- build (mdset/nm/strip) into ${filename} as one rule, and move ${filename}.gz
into separate rule
- rename MDSET.${filename}.nosymbols -> MDSET_NOSYMBOLS.${filename}
- rename MDSET.${filename}.post -> MDSET_POST.${filename}, and don't do
suffix handling here
- rework suffix handling:
- rename MDSET.${filename}.suffixes -> MDSET_SUFFIXES.${filename},
and change from list of suffixes to list of "suffix cmdtobuildsuffix",
where cmdtobuildsuffix is the name of the variable containing the
command to build ${filename}.${suffix} (available as "${.TARGET}").
- for each ${filename}.${suffix}, depend upon ${filename} and use
${cmdtobuildsuffix} to create the former.
- add separate ${filename}.${suffix}.gz rule
- mipsco & pmax: rename "install.gz" to "netbsd-INSTALL.gz", for
consistency and so the target to build the mdset kernel doesn't get
confused with general "install" target

yet another distrib overhaul:
- move guts of distrib/Makefile.inc to distrib/common/Makefile.distrib
(fixes problem caused by implicit include of ../Makefile.inc in certain
submake conditions triggered by makefiles not yet in tree)
- removed mkdir of ${RELEASEDIR}/*; rely upon "snap_pre" target of
etc/Makefile to create all the release directories
- renamed RELINSTALL to RELEASE_INSTALL
- renamed FLOPPYINSTDIR to FLOPPY_RELEASEDIR
- renamed MDSETDIR to MDSET_RELEASEDIR
- removed ITARGET
- move release target from top level to appropriate subdirectory
- ensure release target has correct depends
- replace miniroot's IMAGE_MD_POST with common/Makefile.image IMAGEPOSTBUILD
- Makefile.image: add realall: ${IMAGE}

replace _SRC_TOP_ with NETBSDSRCDIR, since the latter is the "public" version

Makefile.mdset:
replace
TARGETS = KERNEL IMAGE [...]
with
MDTARGETS = KERNEL IMAGE FILENAME [...]
If FILENAME is "-", use "netbsd.${KERNEL}" as the target filename

The rest:
Update for new MDTARGETS syntax. In some cases, the kernel
name from the "old" method will be used to override the default.

- don't pull in <bsd.prog.mk> in Makefile.mdset; do that in the caller instead
- renamed optional post-strip action variable from ${KERNEL}.post to
netbsd.${KERNEL}.post

convert to using distrib/common/Makefile.mdset

Convert to using ${MDSETIMAGE}.

Provide a default value for $MDSETIMAGE and pull in bsd.own.mk to have
it overriden as needed for cross/-current builds.

Add prep installer

Sync with HEAD.