Allow specification of a non-default boto file in chromeos_make

This is needed because our GS bucket needs a different auth key from the
ChromeOS bucket.

(SkipBuildbotRuns)

R=epoger@google.com

Review URL: https://codereview.chromium.org/16975017

git-svn-id: http://skia.googlecode.com/svn/trunk@9692 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed