tdf#120703 (PVS): handle failed realloc

V701 realloc() possible leak: when realloc() fails in allocating memory,
     original pointer 'm_pBuffer' is lost. Consider assigning realloc()
     to a temporary pointer.

Change-Id: I8a18e1472072456bfe9f32d822f185cabd24d6ed
Reviewed-on: https://gerrit.libreoffice.org/62114Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
Tested-by: Mike Kaganski <mike.kaganski@collabora.com>

ucb/source/ucp/ftp/ftpurl.cxx

@@ -88,7 +88,10 @@ int MemoryContainer::append(
             m_nLen+=1024;
         } while(m_nLen < tmp);
 
-        m_pBuffer = std::realloc(m_pBuffer,m_nLen);
+        if (auto p = std::realloc(m_pBuffer, m_nLen))
+            m_pBuffer = p;
+        else
+            return 0;
     }
 
     memcpy(static_cast<sal_Int8*>(m_pBuffer)+m_nWritePos,