net/findomain: fix build on powerpc
= note: ld: error: undefined symbol: __atomic_is_lock_free
>>> referenced by threads_pthread.c
>>> libcrypto-lib-threads_pthread.o:(CRYPTO_atomic_or) in archive /wrkdirs/usr/ports/net/findomain/work/target/release/deps/libopenssl_sys-049131838f14b8ea.rlib
>>> referenced by threads_pthread.c
>>> libcrypto-lib-threads_pthread.o:(CRYPTO_atomic_load) in archive /wrkdirs/usr/ports/net/findomain/work/target/release/deps/libopenssl_sys-049131838f14b8ea.rlib