MFC r256690:

MFC r256690:
  Add an automatic resize support to the GEOM_PART class.

  When parent provider has been resized, the scheme specific G_PART_RESIZE
  method does an update of scheme's metadata. But all changes are not saved
  to disk, until `gpart commit` will be called.

MFC r265336:
  Add an advice what to do when partition was automatically resized.

git-svn-id: svn://svn.freebsd.org/base/stable/10@265912 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f