jbd: initial commit of the package
jbd: initial commit of the package

Change-Id: Ic7b4f6fdb42f830f9d7ee4f0d75a5eb6ef576182
Reviewed-on: https://go-review.googlesource.com/48691
Reviewed-by: Han-Wen Nienhuys <3269a793d567baa2fa5b041e3e5e0a5039790a2f@google.com>

golang/scratch