Undefined reference to pthread_atfork`

Question

Using g++ version 4.9 in Ubuntu, when compiling a C++ source file named test.cpp that needs a shared library named libUtils.so (which in its turn needs Open MPI shared library, hence the parameter -Wl,-rpath-link,/home/dummy/openmpi/build/lib ) as follows:

g++ test.cpp -lUtils -Wl,-rpath-link,/home/dummy/openmpi/build/lib

An error is thrown /home/dummy/openmpi/build/lib/libopen-pal.so.20: undefined reference to pthread_atfork.

I passed -pthread and -lpthread to g++ but none of these solved the error.