Rework DEFAULT_FROM due to dependence on FLAGS_board. Exit out if FLAGS_from doesn't exist. Use FLAGS_from in place of DEFAULT_from later on.
Rework DEFAULT_FROM due to dependence on FLAGS_board.
Exit out if FLAGS_from doesn't exist.
Use FLAGS_from in place of DEFAULT_from later on.

Review URL: http://codereview.chromium.org/651079

coreos/scripts,endocode/scripts,fivethreeo/scripts,mjg59/scripts,andrejro/coreos--scripts,marineam/coreos-scripts,smilart/scripts,marineam/coreos-scripts,coreos/scripts,bcwaldon/coreos-scripts,trnubo/scripts,gtank/scripts,trnubo/scripts,bcwaldon/coreos-scripts,fivethreeo/scripts,crawford/scripts,zhang0137/scripts,crawford/scripts,trnubo/scripts,BugRoger/scripts,gtank/scripts,marineam/coreos-scripts,smilart/scripts,sigma/coreos-scripts,smilart/scripts,zhang0137/scripts,vmware/coreos-scripts,mjg59/scripts,mjg59/scripts,andrejro/coreos--scripts,sigma/coreos-scripts,nicescale/scripts,BugRoger/scripts,zhang0137/scripts,vmware/coreos-scripts,glevand/coreos--scripts,endocode/scripts,crawford/scripts,endocode/scripts,andrejro/coreos--scripts,bcwaldon/coreos-scripts,nicescale/scripts,fivethreeo/scripts,BugRoger/scripts,nicescale/scripts,mischief/scripts,glevand/coreos--scripts,mischief/scripts,mischief/scripts,vmware/coreos-scripts,sigma/coreos-scripts,gtank/scripts