Add a lock file to prevent multiple copies of naclports being run at the same time.
Add a lock file to prevent multiple copies of naclports being run at the same time.

R=bradnelson@google.com

Review URL: https://codereview.chromium.org/444963002

git-svn-id: 84b3587ce119b778414dcb50e18b7479aacf4f1d@1549 7dad1e8b-422e-d2af-fbf5-8013b78bd812

dtkav/naclports,dtkav/naclports,Schibum/naclports,kuscsik/naclports,Schibum/naclports,Schibum/naclports,yeyus/naclports,kuscsik/naclports,Schibum/naclports,kuscsik/naclports,Schibum/naclports,kuscsik/naclports,dtkav/naclports,Schibum/naclports,yeyus/naclports,yeyus/naclports,dtkav/naclports,yeyus/naclports,yeyus/naclports,dtkav/naclports,yeyus/naclports,kuscsik/naclports