virsh: Convert VSH_POOL_ macro to VIRSH_COMMON_OPT_
    
    Commit id's 'cf793b00', 'e178688f', 'f9a6110f', '5372d49', and 'e193735'
    added new VSH_POOL_ macros; however, it was pointed out after push that
    commit id '834c5720' preferred use of VIRSH_ for the prefix over VSH_.
    
    So this patch just changes the VSH_ to VIRSH_ and it changes the naming
    format from VIRSH_<opt>_OPT_COMMON to VIRSH_COMMON_OPT_<opt>.
    
    Signed-off-by: John Ferlan <jferlan@redhat.com>