Spurious / in a pool target path makes life difficult for apps using the
GetVolByPath, and doing other path based comparisons with pools. This
has caused a few issues for virt-manager users:
https://bugzilla.redhat.com/show_bug.cgi?id=494005https://bugzilla.redhat.com/show_bug.cgi?id=593565
Add a new util API which removes spurious /, virFileSanitizePath. Sanitize
target paths when parsing pool XML, and for paths passed to GetVolByPath.
v2: Leading // must be preserved, properly sanitize path=/, sanitize
away /./ -> /
v3: Properly handle starting ./ and ending /.
v4: Drop all '.' handling, just sanitize / for now.