Reimplement xfs_info by returning a hash table of values (rather than
a limited struct), and by writing it in OCaml with PCRE which makes
string parsing a lot simpler. This will now flexibly return all the
fields from the underlying xfs_info command, even (hopefully) future
fields.
Note the field values are returned as strings, because the actual
fields in xfs_info output are fairly random and free-form. There is a
trade off here between returning as much information as we can, and
requiring the user to do a bit of (simple) field parsing.
Fixes: https://issues.redhat.com/browse/RHEL-143673
(cherry picked from commit dfd2700616)
aac2ec6820