Fix zip_build handling of comma separated strings.
Fix zip_build handling of comma separated strings.

Was mishandling quoted args like
"F1, F2, F3" such as in
http://chromegw.corp.google.com/i/client.o3d/builders/dbg-d3d-gtv/builds/169/steps/package_build/logs/stdio

BUG=


Review URL: https://chromiumcodereview.appspot.com/10914071

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@154783 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build