efee1af storage: implement rudimentary glusterfs pool refresh

Authored and Committed by ericb 10 years ago
    storage: implement rudimentary glusterfs pool refresh
    
    Actually put gfapi to use, by allowing the creation of a gluster
    pool.  Right now, all volumes are treated as raw and directories
    are skipped; further patches will allow peering into files to
    allow for qcow2 files and backing chains, and reporting proper
    volume allocation.  This implementation was tested against Fedora
    19's glusterfs 3.4.1; it might be made simpler by requiring a
    higher minimum, and/or require more hacks to work with a lower
    minimum.
    
    * src/storage/storage_backend_gluster.c
    (virStorageBackendGlusterRefreshPool): Initial implementation.
    (virStorageBackendGlusterOpen, virStorageBackendGlusterClose)
    (virStorageBackendGlusterRefreshVol): New helper functions.
    
    Signed-off-by: Eric Blake <eblake@redhat.com>