generate_au_zip.py: Include dumpe2fs.

dumpe2fs is used to compute the size of and ext2 filesystem when
extracting Chrome OS images.

BUG=b:24478450
TEST=./build_library/generate_au_zip.py ; ./build_library/test_au_zip.py

Change-Id: I8a8390c8eca546900f3725457cf48925ac5dc0a7
Reviewed-on: https://chromium-review.googlesource.com/302805
Commit-Ready: Alex Deymo <deymo@chromium.org>
Tested-by: Alex Deymo <deymo@chromium.org>
Reviewed-by: Matthew Sartori <msartori@chromium.org>
1 file changed