fix three backend mailnews memory leaks, r/a=sspitzer, sr=mscott 228561

mailnews/base/search/src/nsMsgSearchAdapter.cpp

@@ -348,6 +348,7 @@ nsMsgSearchAdapter::GetSearchCharsets(PRUnichar **srcCharset, PRUnichar **dstCha
         {
             nsXPIDLCString folderCharset;
             folder->GetCharset(getter_Copies(folderCharset));
+      PR_Free(*dstCharset);
             *dstCharset = ToNewUnicode(folderCharset);
         }
 	}
@@ -359,7 +360,10 @@ nsMsgSearchAdapter::GetSearchCharsets(PRUnichar **srcCharset, PRUnichar **dstCha
 	// was undefined or unavailable.)
   // ### well, it's not really anymore. Is there an equivalent?
   if (!nsCRT::strcmp(*dstCharset, m_defaultCharset.get()))
+  {
+    PR_Free(*dstCharset);
     *dstCharset = nsCRT::strdup(*srcCharset);
+  }
 
 	if (m_forceAsciiSearch)
 	{
@@ -370,6 +374,7 @@ nsMsgSearchAdapter::GetSearchCharsets(PRUnichar **srcCharset, PRUnichar **dstCha
 		// If the dest csid is ISO Latin 1 or MacRoman, attempt to convert the 
 		// source text to US-ASCII. (Not for now.)
 		// if ((dst_csid == CS_LATIN1) || (dst_csid == CS_MAC_ROMAN))
+    PR_Free(*dstCharset);
     *dstCharset = nsCRT::strdup(NS_LITERAL_STRING("us-ascii").get());
 	}
   return NS_OK;

mailnews/base/util/nsMsgIdentity.cpp

@@ -607,6 +607,7 @@ nsMsgIdentity::getFolderPref(const char *prefname, char **retval, PRBool mustHav
     {
       nsCOMPtr <nsIMsgFolder> msgFolder;
       rv = server->GetMsgFolderFromURI(folderResource, *retval, getter_AddRefs(msgFolder));
+      PR_Free(*retval);
       if (NS_SUCCEEDED(rv))
         return msgFolder->GetURI(retval);
     }

mailnews/imap/src/nsImapProtocol.cpp

@@ -5456,6 +5456,7 @@ void nsImapProtocol::OnStatusForFolder(const char *mailboxName)
   nsImapMailboxSpec *new_spec = GetServerStateParser().CreateCurrentMailboxSpec(mailboxName);
   if (new_spec && m_imapMailFolderSink)
     m_imapMailFolderSink->UpdateImapMailboxStatus(this, new_spec);
+  NS_IF_RELEASE(new_spec);
 }