Can’t build the newest ports powerdns-recursor 4.6.0 and dnsdist 1.7.0 with libressl as default ssl library. Same error: 

mv -f $depbase.Tpo $depbase.Po
depbase=`echo credentials.o | sed 's|[^/]*$|.deps/&|;s|\.o$||'`;\
c++ -std=c++17 -DHAVE_CONFIG_H -I.  -I/usr/local/include/lua52  -I./ext/yahttp -pthread     -O3 -Wall -pthread -DSYSCONFDIR=\"/usr/local/etc/pdns\"  -I./ext/json11 -I./ext/protozero/include -I./ext/yahttp -I/usr/local/include  -DBOOST_CONTAINER_USE_STD_EXCEPTIONS  -I/usr/local/include/lua52   -isystem /usr/local/include -DSYSCONFDIR=\"/usr/local/etc/pdns\" -DPKGLIBDIR=\"/usr/local/lib/pdns-recursor\" -DLOCALSTATEDIR=\"/var/run\" -DNODCACHEDIR=\"/var/lib/pdns-recursor\" -fPIE -DPIE -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 --param ssp-buffer-size=4 -fstack-protector -Wall -Wextra -Wshadow -Wno-unused-parameter -Wmissing-declarations -Wredundant-decls -g -O2 -O2 -pipe -fstack-protector-strong -isystem /usr/local/include -fno-strict-aliasing  -isystem /usr/local/include  -MT credentials.o -MD -MP -MF $depbase.Tpo -c -o credentials.o credentials.cc &&\
mv -f $depbase.Tpo $depbase.Po
credentials.cc:99:90: error: use of undeclared identifier 'EVP_PKEY_SCRYPT'
  auto pctx = std::unique_ptr<EVP_PKEY_CTX, void (*)(EVP_PKEY_CTX*)>(EVP_PKEY_CTX_new_id(EVP_PKEY_SCRYPT, nullptr), EVP_PKEY_CTX_free);