Merge branch 'tb/log-G-binary'

Merge branch 'tb/log-G-binary'

"git log -G<regex>" looked for a hunk in the "git log -p" patch
output that contained a string that matches the given pattern.
Optimize this code to ignore binary files, which by default will
not show any hunk that would match any pattern (unless textconv or
the --text option is in effect, that is).

* tb/log-G-binary:
  log -G: ignore binary files