Patches that install drivers (via add_drv) must currently test for the
case where "patchadd -R" points to a diskless client root.  This is done
as follows:

	if [ "$ROOTDIR" = / ]; then
		# Not in diskless client root; install driver.
	else
		# Diskless client root; do not install driver.
	fi

Due to Ashanti's use of patches in the upgrade process and its support
of zones, a different procedure must be used for all patches on S10 FCS
and later:

	ZONENAME=global
	[ -x /sbin/zonename ] && ZONENAME=`/sbin/zonename`
	if [ "$ROOTDIR" = / -o "$ROOTDIR" = /a ] &&
	   [ $ZONENAME = global ]; then
		# Not in a diskless client root or zone; install driver.
	else
		# Diskless client root or non-global zone; no driver.
	fi