installer: chromeos-common: support blocksize function.

The write_gpt.sh in new release image expects to have blocksize function
in chromeos-common.sh but old factory branch didn't support it yet.

BUG=b:119292628
TEST=create a diskimg by `make_factory_package.sh` in chroot.
Change-Id: I0f09d59a400b6969266d7c2cdc0d862bf890c70e
Reviewed-on: https://chromium-review.googlesource.com/c/1345869
Reviewed-by: Marco Chen <marcochen@chromium.org>
Commit-Queue: Marco Chen <marcochen@chromium.org>
Tested-by: Marco Chen <marcochen@chromium.org>
1 file changed