autostart: Use ArchiveSplit from BackupPC's conf

This is probably a bug; I ought to report it if it isn't
already fixed.

BackupPC_archiveStart

@@ -100,7 +100,7 @@ my %ArchiveReq = (
     compext     => $bpc->{Conf}{ArchiveComp} eq 'none' ? ''
                     : ($bpc->{Conf}{ArchiveComp} eq 'gzip' ? '.gz' : '.bz2'),
     parfile     => $bpc->{Conf}{ArchivePar},
-    splitsize   => '0000000',
+    splitsize   => $bpc->{Conf}{ArchiveSplit} * 1000000,
     host        => $ArchiveHost,
     HostList    => \@HostList,
     BackupList  => \@BackupList,

backup-manager.py

@@ -182,7 +182,9 @@ def start_archive(hosts):
         except KeyError:
             username = 'nobody'
 
-    cmd = ['/usr/share/backuppc/bin/BackupPC_archiveStart', 'archives3',
+    scriptdir = os.path.dirname(sys.argv[0])
+
+    cmd = [os.path.join(scriptdir, 'BackupPC_archiveStart'), 'archives3',
            username]
     cmd.extend(hosts)