Makefile.inc and bsd.port.arch.mk without infinite recursion.
- use simpler pattern to test for arch stuff, we just need the values, so
.for A B in ${MACHINE_ARCH} ${ARCH}
is enough and avoids the setting of intermediate variables.
- new PROPERTIES variable that's easy to test with e.g. if ${PROPERTIES:Mapm}
dpb coalesces build dependencies over MULTI_PACKAGES: if we don't substract
from MULTI_PACKAGES, this can lead to bootstrap loops.
Case in point: sysutils/gamin, whose build relies on "no_server" to be
available as a dependency for glib2/gtk+2.
(but IGNORED stuff is properly kept as MULTI_PACKAGES, since it's mostly
intended to avoid strange arch errors)
