torture: Make kvm-find-errors.sh report link-time undefined symbols

This commit makes kvm-find-errors.sh check for and report undefined
symbols that are detected at link time.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh

@@ -30,9 +30,9 @@ editor=${EDITOR-vi}
 files=
 for i in ${rundir}/*/Make.out
 do
-	if egrep -q "error:|warning:" < $i
+	if egrep -q "error:|warning:|^ld: .*undefined reference to" < $i
 	then
-		egrep "error:|warning:" < $i > $i.diags
+		egrep "error:|warning:|^ld: .*undefined reference to" < $i > $i.diags
 		files="$files $i.diags $i"
 	fi
 done

tools/testing/selftests/rcutorture/bin/parse-build.sh

@@ -39,7 +39,8 @@ fi
 grep warning: < $F > $T/warnings
 grep "include/linux/*rcu*\.h:" $T/warnings > $T/hwarnings
 grep "kernel/rcu/[^/]*:" $T/warnings > $T/cwarnings
-cat $T/hwarnings $T/cwarnings > $T/rcuwarnings
+grep "^ld: .*undefined reference to" $T/warnings | head -1 > $T/ldwarnings
+cat $T/hwarnings $T/cwarnings $T/ldwarnings > $T/rcuwarnings
 if test -s $T/rcuwarnings
 then
 	print_warning $title build errors: