Emulator 32-bit check fails on Ubuntu 14.04

android-rebuild.sh was failing due to a slight difference between
the output of the file command on Ubuntu 12.04 and 14.04.  This
change should handle both now.

Change-Id: If5bf442849272e0e87c233e2512ad2d8decb4670
Merge "Emulator 32-bit check fails on Ubuntu 14.04"