documentation: Expand on scheduler/RCU deadlock requirements

This commit adds a second option for avoiding scheduler/RCU deadlocks,
namely that preemption be disabled across the entire RCU read-side
critical section in question.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

path: root/astraceroute/Makefile

astraceroute-libs =	-lGeoIP \
			-lpthread \
			-lz

astraceroute-objs =	xmalloc.o \
			ioops.o \
			xutils.o \
			proto_none.o \
			tprintf.o \
			bpf.o \
			str.o \
			dev.o \
			geoip.o \
			ring_rx.o \
			ring.o \
			astraceroute.o