update_engine: Disable puffin in minor version 4

This patch disables puffin for minor version 4, but keeps BROTLI_BSDIFF in the
same minor version.  Also adds puffin for minor version 5, but it does not
enable it.

Bug: 30989362
BUG=b:72815313
BUG=chromium:810184
TEST=update_engine unittests pass
TEST=update_payload unittests pass
TEST=test_paycheck.sh on two images with minor version 4 pass
TEST=brill_update_payload generate/verify pass

Change-Id: I814fc126d67207501d419cff9c575cd13d877b48
Reviewed-on: https://chromium-review.googlesource.com/907223


Commit-Ready: Amin Hassani <ahassani@chromium.org>
Tested-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
(cherry picked from commit 77d7cbce)