Instead of just warning that apt failed, tell why

With the lsof we should see which process was holding the lock.
After that we can disable this source of problems.

Change-Id: Ie6a014bdb101e6230139569c0e4ea51a57089c30
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
Reviewed-by: Heikki Halmet <heikki.halmet@qt.io>
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@qt.io>

coin/provisioning/qtci-linux-Ubuntu-16.04-x86_64/02-apt.sh

@@ -159,6 +159,7 @@ catch || {
         ;;
         $ExceptionAPT)
             echo "Failed to install package."
+            sudo lsof /var/lib/dpkg/lock
             exit 1;
         ;;
         $ExceptionSED)