C git considers not only files containing NUL bytes as binary but also
files containing lone CRs. Implement this also for JGit.
C git additionally counts printable vs. non-printable characters and
considers files that have non_printable_count > printable_count / 128
also as binary. This is not implemented because such counting probably
only makes sense if one looks at the full file or blob content. The
Auto[CR]LF* streams in JGit look only at the first few KiB of a stream
in order not to buffer too much.
For the C git implementation, see [1].
[1] https://github.com/git/git/blob/7e27bd589d/convert.c#L35
Bug: 576971
Change-Id: Ia169b59bdbf1477f32ee2014eeb8406f81d4b1ab
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>