[PATCHES] fget()-to-fdget() whack-a-mole

[Al Viro]

	fget()/fget_raw() should be used when we are going to keep
struct file reference; for temporary references fdget()/fdget_raw()
ought to be used.  That kind of stuff keeps cropping up on a regular
basis, and it needs periodic pruning.

	The current pile is in vfs.git #work.fd; individual patches
in followups.