Kernel - Fix issues with vnode_pager_setsize() (effects NFS only)
* When truncating a file to non-zero length, if the filesystem calls
vnode_pager_setsize() with a truncation offset that is not a
multiple of DEV_BSIZE vnode_pager_setsize() will improperly clear
the dirty bit for the overlapping DEV_BSIZE'd block in the VM page
straddling the truncation point.
This only effects NFS. The fsx filesystem test was failing due to
a lost dirty page after a truncation.
Reported-by: Antonio Huete Jimenez <tuxillo@quantumachine.net>