Fix DIOCGMEDIASIZE and DIOCGSECTORSIZE ioctls to work for all disk devices. This fixes the problem with these ioctls returning EINVAL for plain slice devices with no disklabel on them.
Fix DIOCGMEDIASIZE and DIOCGSECTORSIZE ioctls to work for all
disk devices. This fixes the problem with these ioctls returning
EINVAL for plain slice devices with no disklabel on them.

The patch incorporates improvements and style fixes from BDE.

Reviewed by:	bde
Approved by:	obrien (mentor)

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