Using unordered_map at sgxsdk 1.8

Hi,
I am using sgxsdk 1.8 at ubuntu16.04.
I want to use unordered_map at this version, however, I can't successfully build the execution.
The error is :
In file included from /opt/intel/sgxsdk/include/stlport/stl/_slist.h:826:0,
from /opt/intel/sgxsdk/include/stlport/stl/_hashtable.h:38,
from /opt/intel/sgxsdk/include/stlport/stl/_unordered_map.h:24,
from /opt/intel/sgxsdk/include/stlport/unordered_map:28,
from Enclave/Enclave.cpp:4:
/opt/intel/sgxsdk/include/stlport/stl/_slist.c: In function ‘void stlpmtx_std::priv::_Slist_merge(stlpmtx_std::slist<_Tp, _Alloc>&, stlpmtx_std::slist<_Tp, _Alloc>&, _StrictWeakOrdering)’:
/opt/intel/sgxsdk/include/stlport/stl/_slist.c:151:39: warning: typedef ‘_Node_base’ locally defined but not used [-Wunused-local-typedefs]
typedef _STLP_PRIV _Slist_node_base _Node_base;
^
Enclave/Enclave.cpp: At global scope:
Enclave/Enclave.cpp:20:6: error: ‘unodered_map’ in namespace ‘stlpmtx_std’ does not name a template type
std::unodered_map wq;
^
Makefile:312: recipe for target 'Enclave/Enclave.o' failed
make: *** [Enclave/Enclave.o] Error 1

Does anyone know how to solve this problem?
Under the newest sgxsdk version, I can successfully build the code.
Thanks!