coverity#708240 Uninitialized pointer field

Change-Id: I127cfc84412984e9c190f3e5b2e37cf76ebf82f1

stoc/source/security/lru_cache.h

@@ -127,6 +127,7 @@ inline lru_cache< t_key, t_val, t_hashKey, t_equalKey >::lru_cache(
     ::std::size_t size ) SAL_THROW(())
     : m_size( 0 )
     , m_block( 0 )
+    , m_tail( 0 )
 {
     setSize( size );
 }