Newer perl versions have problem with split without arg

git-svn-id: svn://svn.code.sf.net/p/fhem/code/trunk@1164 2b470e98-0d58-463d-a4d8-8e2adae1ed80

fhem/FHEM/99_updatefhem.pm

@@ -41,6 +41,8 @@ CommandUpdatefhem($$)
   my @commandchain = split(/ +/,$param);
 
   #  Check if the first parameter is "backup"
+  if($param) {
+    my @commandchain = split(/ +/,$param);
     if(uc($commandchain[0]) eq "BACKUP") {
       my $backupdir = AttrVal("global", "backupdir", "/tmp/FHEM_Backup");
       # create the backupfolder
@@ -71,6 +73,7 @@ CommandUpdatefhem($$)
         $param = $commandchain[1];
       }
     }
+  }
 
   # Read in the OLD filetimes.txt
   my %oldtime;