Error in make deb_psw_pkg: recipe for target 'qve_wrapper' failed

Hello, I'm trying to build SGX PSW. I have Ubuntu 18.04 with SGX hardware support but I DON'T have Flexible Launch Control. I successfully installed both SGX driver and SGX SDK 2.13, but I'm having hard times trying to install PSW. This is the output message:

```
make[2]: Entering directory '/home/torsec/linux-sgx/external/dcap_source/QuoteVerification/QvE'
/usr/local/bin/ld: /opt/intel/sgxsdk/lib64/libsgx_pthread.a(pthread.o): in function `_pthread_wakeup(unsigned long) [clone .part.0]':
pthread.cpp:(.text._Z15_pthread_wakeupm.part.0+0x2d): undefined reference to `pthread_wakeup_ocall'
collect2: error: ld returned 1 exit status
Makefile:140: recipe for target 'qve.so' failed
make[2]: *** [qve.so] Error 1
make[2]: Leaving directory '/home/torsec/linux-sgx/external/dcap_source/QuoteVerification/QvE'
Makefile:37: recipe for target 'all' failed
make[1]: *** [all] Error 2
make[1]: Leaving directory '/home/torsec/linux-sgx/external/dcap_source/QuoteVerification'
Makefile:64: recipe for target 'qve_wrapper' failed
make: *** [qve_wrapper] Error 2
```

Any suggestions?
Thanks in advance.