How do I get rid of this error ?

"/GCC/lib/gcc/ppc-amigaos/11.2.0/newlib/lib/libstdc++.so: undefined reference to `__gthread_cond_broadcast'
/GCC/lib/gcc/ppc-amigaos/11.2.0/newlib/lib/libstdc++.so: undefined reference to `__gthread_cond_destroy'
/GCC/lib/gcc/ppc-amigaos/11.2.0/newlib/lib/libstdc++.so: undefined reference to `__gthread_cond_init'
/GCC/lib/gcc/ppc-amigaos/11.2.0/newlib/lib/libstdc++.so: undefined reference to `__gthread_cond_wait'
/GCC/lib/gcc/ppc-amigaos/11.2.0/newlib/lib/libstdc++.so: undefined reference to `__gthread_cond_signal'"

I'm trying to compile (g++) a cpp program using cpp shared object .so lib.