pcp updates: pmdaxfs - use persistent dm and md mapped names for xfs.perdev

Changes committed to git://git.pcp.io/mgoodwin/pcp master

commit b4b846a6e9d88de7c2290295c863add688ec9130
Author: Mark Goodwin <[email protected]>
Date:   Thu Nov 24 16:16:25 2016 +1100

    qa: persistent dm and md device naming for xfs.perdev metrics

    Also committed new tarballs linux/xfs-root-00[12].tgz for use
    by qa/987 and qa/988 since the xfs PMDA now needs to read the
    dm name mappings from below /sys. No changes to the tests, but
    the qualified output  has been remade agaist the new tarballs.

        modified:   qa/987.out
        modified:   qa/988.out
        modified:   qa/linux/xfs-root-001.tgz
        modified:   qa/linux/xfs-root-002.tgz

commit 0b53f5b4ae8494ecbf1a1d4362a87ee5a111bb49
Author: Mark Goodwin <[email protected]>
Date:   Thu Nov 24 16:10:28 2016 +1100

    pmdaxfs: use persistent dm and md device names for xfs.perdev

    dm-xx device names are not persistent. So use the mapped name for
    these devices as the instance names in xfs.perdev.*. Also now uses
    the full path to the device, since that could be ambiguous otherwise.
    This is now also consistent with the device instance naming used for
    filesys.* metrics.