RELEASEVARS variable, and commands related to printing the values of
the variables whose names are in RELEASEVARS.
Add an awk script to remove noise printed by "make -j" or high levels
of MAKEVERBOSE, so we get only the variables names and values. The
values are escaped so that variables containing embedded newlines,
quotation marks, and backslashes, are passed through safely.
Adapt src/etc/Makefile and src/Makefile to use the new ${PRINT_PARAMS}
command defined in src/etc/Makefile.params.
Now ${DESTDIR}/etc/release and the params file in the top-level
.OBJDIR should never contain unwanted noise, even after a build with
MAKEVERBOSE=4.
apb