build error [OSX]

[Vittorio La Barbera]

Failing when running make -j4:

[ 50%] Built target mss
[ 58%] Linking CXX shared library ../../python/pymss.dylib
[ 66%] Linking CXX executable render
Undefined symbols for architecture x86_64:
"___kmpc_for_static_fini", referenced from:
_.omp_outlined. in EnvManager.cpp.o
_.omp_outlined..2 in EnvManager.cpp.o
_.omp_outlined..3 in EnvManager.cpp.o
_.omp_outlined..4 in EnvManager.cpp.o
"___kmpc_for_static_init_4", referenced from:
_.omp_outlined. in EnvManager.cpp.o
_.omp_outlined..2 in EnvManager.cpp.o
_.omp_outlined..3 in EnvManager.cpp.o
_.omp_outlined..4 in EnvManager.cpp.o
"___kmpc_fork_call", referenced from:
EnvManager::Steps(int) in EnvManager.cpp.o
EnvManager::StepsAtOnce() in EnvManager.cpp.o
EnvManager::GetMuscleTorques() in EnvManager.cpp.o
EnvManager::GetDesiredTorques() in EnvManager.cpp.o
........
clang-9: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [../python/pymss.dylib] Error 1
make[1]: *** [python/CMakeFiles/pymss.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....
Undefined symbols for architecture x86_64:
"___kmpc_fork_call", referenced from:

Any clues?