K 10
svn:author
V 6
kevans
K 8
svn:date
V 27
2019-01-09T22:31:10.812065Z
K 7
svn:log
V 561
libbe(3): move altroot augmentation bits around a little bit

We could perhaps have a method that does this given a dataset, but it's yet
clear that we'll always want to bypass the altroot when we grab the
mountpoint. For now, we'll refactor things a bit so we grab the altroot
length when libbe is initialized and have a common method that does the
necessary augmentation (replace with / if it's the root, return a pointer to
later in the string if not).

This will be used in some upcoming work to make be_mount work properly for
deep BEs.

MFC after:	1 week

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