Undefined symbols for arcitecture x86_64 when I try to use GRANSAC code from github

I'm trying to use GRANSAC(Generic RANSAC) from this github repository. https://github.com/drsrinathsridhar/GRANSAC When I build with cmake, this error happens and I don't know how to solve it.

Undefined symbols for architecture x86_64: "_omp_get_max_threads", referenced from: GRANSAC::RANSAC::Estimate(std::__1::vector, std::__1::allocator >

const&) in LineFittingSample.cpp.o GRANSAC::RANSAC::RANSAC() in LineFittingSample.cpp.o "_omp_get_thread_num", referenced from: GRANSAC::RANSAC::Estimate(std::__1::vector, std::__1::allocator > const&) in LineFittingSample.cpp.o "_omp_set_dynamic", referenced from: GRANSAC::RANSAC::Estimate(std::__1::vector, std::__1::allocator > const&) in LineFittingSample.cpp.o "_omp_set_num_threads", referenced from: GRANSAC::RANSAC::Estimate(std::__1::vector, std::__1::allocator > const&) in LineFittingSample.cpp.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation) make[2]: * [LineFittingSample] Error 1 make[1]: * [CMakeFiles/LineFittingSample.dir/all] Error 2 make: *** [all]

Error 2

Environment: MacOS Mojave ver 10.14.16