Merge the two Makefiles that were mostly copies of each others.
The reason to do this was to add support for cleaning up the config.cache
files when the build environment (as determined by uname -srm) changes.

branches: 1.6.6;
Actually use timestamp file's timestamps so that things rebuild correctly.

Use ${TOOL_AWK} instead of ${AWK} or plain "awk" in make commands.
Pass AWK=${TOOL_AWK:Q} to shell scripts that use awk.

Verify that MAKEFLAGS contains "-j" before trying to manipulate it
with :C///.

pass the "-j" flag down to gmake. you can force -j option to
gmake by setting GMAKE_J_ARGS=-jN.


discussed with matt@ and a few others.

XXX: this is kind of hacky, as it will fork off more processes than
XXX: "-jN" says to, but there's no real way to get parallelism in
XXX: both the tools/gcc build and the rest of the build without
XXX: this.

branches: 1.2.20;
put MAKE_ARGS in the gmake command line.

initial wrapper for gmake-requiring tools. probably does not yet
work on all currently supported netbsd build hosts.

XXX current issues:
XXX - calls /usr/bin/env -i directly, mostly to wipe-out MAKEFLAGS
XXX from the environment (usually set by the buildwrapper to
XXX "-de -m <path-to>/share/mk"