Cirrus-CI: Check for final "Uptime" message

The last thing printed by the kernel after shutdown is Uptime: <time>.
Check also for this to ensure that shutdown is successful.  A test
branch of mine panicked during shutdown, but still reported success in
Cirrus-CI.

Differential Revision:

tools/boot/ci-qemu-test.sh

@@ -125,7 +125,7 @@ timeout 300 \
         -snapshot -hda $hda 2>&1 | tee ${BOOTLOG}
 
 # Check whether we succesfully booted...
-if grep -q 'Hello world.' ${BOOTLOG}; then
+if grep -q 'Hello world.' ${BOOTLOG} && egrep -q '^Uptime: ' ${BOOTLOG}; then
 	echo "OK"
 else
 	die "Did not boot successfully, see ${BOOTLOG}"