Hibernation: Clean up userland interface (rev. 2)

Hi,

This series of patches is intended to eliminate some design problems with the
hibernation userland interface.

It contains the following changes:
* allow the user space utilities to get the size of the image via ioctl
* introduce ioctls to be used instead of SNAPSHOT_PMOPS
* mark the SNAPSHOT_SET_SWAP_FILE ioctl as deprecated
* introduce new ioctl definitions to replace the wrongly defined ones
* move the definitions of hibernation ioctls to a separate header file located
  in include/linux/ and export them to the user space
The details are in the changelogs.

Comments welcome.

Greetings,
Rafael


-- 
"Premature optimization is the root of all evil." - Donald Knuth