Build fails with LibreSSL: ./.libs/libopusurl.so: undefined reference to `BIO_meth_set_puts'

LibreSSL 2.6.5, Gentoo Linux.

src/http.c: In function ‘op_bio_retry_new’:
src/http.c:1540:3: warning: implicit declaration of function ‘BIO_set_init’; did you mean ‘BIO_sock_init’? [-Wimplicit-function-declaration]
   BIO_set_init(_b,1);
   ^~~~~~~~~~~~
   BIO_sock_init
src/http.c:1544:3: warning: implicit declaration of function ‘BIO_set_data’; did you mean ‘BIO_set_ex_data’? [-Wimplicit-function-declaration]
   BIO_set_data(_b,NULL);
   ^~~~~~~~~~~~
   BIO_set_ex_data

and so on.

Full build.log

See also: https://bugs.gentoo.org/588768