Bug 1040413 - Do not cast ANDROID_VERSION to int; r=nalexander

Ideally it should be converted to an int. But empty variables need to
work. The rest of the tree uses string comparisons.

--HG--
extra : rebase_source : 16701034df6b5047bcd7ca529785ee97b76412ed
extra : amend_source : 9c1cc54c1820dccae514ad06dac5677710e9a8f0