kernel - Adjust UFS and HAMMER to use uiomovebp()
* Add uiomovebp(), a version of uiomove() which is aware of a locked bp
representing the to or from buffer and can work-around issues related
to VM faults causing recursions and deadlocks on the user buffer.
uiomovebp() does not yet detect or handle deadlocks. Implementing
deadlock handling will require a certain degree of finess related to
the vnode and bp locks and we don't want to have to do it unless we
actually deadlock. TODO.
* Adjust UFS, HAMMER, TMPFS, MSDOSFS, NFS, NTFS to use uiomovebp().