Some cleanups from NetBSD:

Some cleanups from NetBSD:
- C99 initializers.
- Change the default volume label from "NO NAME" to "NO_NAME".
- Set OEM String to "BSD4.4 " following the unnamed spacing convention
  in that other OS that suggests "MSWIN4.1"
Also, David Naylor's changes for Clang, mostly changing the signess
of constants.

Submitted by:	Pedro F. Giffuni <giffunip tutopia com>
Clang fixes by:	David Naylor <naylor.b.david gmail com>
Reviewed by:	bde (with some disagreement about Clang issues)
MFC after:	2 weeks