* Set stuff mostly in the environment, not on make(1)'s command line.
This is needed for MACHINE and MACHINE_ARCH (noted by bjh21), and keeps
the mk.conf-overriding-env behavior (suggested by several people).
* Use MAKEFLAGS to make the wrapper script more readable.
* When prepping objdir in tools for the default TOOLDIR value, just make
that objdir; leave the recursive "make obj" for later.
using `uname -s`-`uname -r`-`uname -p || uname -m`. This can be overridden
in mk.conf or the environment, and is used by host tools to ensure that
build hosts do not clobber each other.
* Now that there's an objdir in src/tools, make a default TOOLDIR by creating
"tools.${HOST_OSTYPE}" in the objdir (if it exists) of src/tools. This
means that TOOLDIR is no longer required to be set in a build, though it
still may be set manually if desired.
* Set MKTOOLS to "yes" by default, since the default TOOLDIR is now located
in a known mutable location. This may still be set manually if desired.
just don't build the tools if USETOOLS!=yes. This permits objdirs to
be created even when USETOOLS=no.
* Clean up use of "-m" by specifying it to .MAKEFLAGS: if needed.
Only descend into directories if USE_NEW_TOOLCHAIN is set (allows top level
Makefile to use "-m ${.CURDIR}/share/mk" to get the "correct" <bsd.own.mk>
when descending into src/tools/Makefile).
