_GOMP_barrier issue

_GOMP_barrier

$ CC=/usr/local/bin/gcc-8 python3 setup.py build_ext --inplace && python3 -m nanopy

running build_ext
building 'nanopy.work' extension
creating build
creating build/temp.macosx-10.6-intel-3.6
creating build/temp.macosx-10.6-intel-3.6/nanopy
gcc-8 -fno-strict-aliasing -Wsign-compare -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -arch i386 -arch x86_64 -g -I/Library/Frameworks/Python.framework/Versions/3.6/include/python3.6m -c nanopy/work.c -o build/temp.macosx-10.6-intel-3.6/nanopy/work.o -fopenmp
gcc-8: warning: x86_64 conflicts with i386 (arch flags ignored)
nanopy/work.c: In function 'generate':
nanopy/work.c:602:19: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'const long unsigned int'} [-Wsign-compare]
     for (i = 0; i < work_size; i++) {
                   ^
creating build/lib.macosx-10.6-intel-3.6
creating build/lib.macosx-10.6-intel-3.6/nanopy
gcc-8 -bundle -undefined dynamic_lookup -arch i386 -arch x86_64 -g build/temp.macosx-10.6-intel-3.6/nanopy/work.o -lb2 -o build/lib.macosx-10.6-intel-3.6/nanopy/work.cpython-36m-darwin.so
gcc-8: warning: x86_64 conflicts with i386 (arch flags ignored)
copying build/lib.macosx-10.6-intel-3.6/nanopy/work.cpython-36m-darwin.so -> nanopy
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/runpy.py", line 183, in _run_module_as_main
    mod_name, mod_spec, code = _get_module_details(mod_name, _Error)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/runpy.py", line 142, in _get_module_details
    return _get_module_details(pkg_main_name, error)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/runpy.py", line 109, in _get_module_details
    __import__(pkg_name)
  File "/Users/rbw/nanopy/nanopy/__init__.py", line 112, in <module>
    import nanopy.work
ImportError: dlopen(/Users/rbw/nanopy/nanopy/work.cpython-36m-darwin.so, 2): Symbol not found: _GOMP_barrier
  Referenced from: /Users/rbw/nanopy/nanopy/work.cpython-36m-darwin.so
  Expected in: flat namespace
 in /Users/rbw/nanopy/nanopy/work.cpython-36m-darwin.so