Fix VOLUME_LABEL when BRANCH contains non-alpha
characters, in particular '-' and '.'.

Submitted by:	des
Tested by:	des
MFC after:	3 days
X-MFC-10.1:	yes
Sponsored by:	The FreeBSD Foundation
Eliminate a stale, i386-specific comment.
Fix mis-spelling of bits and types names in the
default_pager_putpages() and swap_pager_putpages().
It is the same fix as was done for vnode_pager_putpages()
in r271586.

Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week