Fix or indicate possible null pointer dereferencing detected by FindBugs

ludovicp

29.11.2008 aa4cddefb7237eea616db2b525539cc7c854d41a

 opends/src/server/org/opends/server/backends/LDIFBackend.java

@@ -636,6 +636,7 @@
        else
        {
          DN matchedDN = null;
          // BUG: parentDN can be null when entering the loop
          while (true)
          {
            parentDN = parentDN.getParentDNInSuffix();