Doesn't work on newer getdns library versions

[rudybroersma]

I am unable to compile danetls on a machine running Debian Bullseye (11). The reason is that getdns_ext_event is missing.

Debian 10:

# dpkg -l | grep getdns
ii  libgetdns-dev                         1.5.1-1

Debian 11:

# dpkg -l | grep getdns
ii  libgetdns-dev:amd64                  1.6.0-2

Compile output on Debian 11 is:

# make clean; make
rm -rf *.o danetls danetls-getdns
cc -g -Wall -Wextra -I. -I/usr/local/openssl/include -I/usr/local/include   -c -o danetls.o danetls.c
cc -g -Wall -Wextra -I. -I/usr/local/openssl/include -I/usr/local/include   -c -o query-ldns.o query-ldns.c
cc -g -Wall -Wextra -I. -I/usr/local/openssl/include -I/usr/local/include   -c -o utils.o utils.c
cc -g -Wall -Wextra -I. -I/usr/local/openssl/include -I/usr/local/include   -c -o tls.o tls.c
cc -g -Wall -Wextra -I. -I/usr/local/openssl/include -I/usr/local/include   -c -o starttls.o starttls.c
cc -g -Wall -Wextra -I. -I/usr/local/openssl/include -I/usr/local/include   -c -o tlsardata.o tlsardata.c
cc -L/usr/local/openssl/lib -L/usr/local/lib -Wl,-rpath -Wl,/usr/local/openssl/lib -Wl,-rpath -Wl,/usr/local/lib -o danetls danetls.o query-ldns.o utils.o tls.o starttls.o tlsardata.o -lssl -lcrypto -lldns
cc -g -Wall -Wextra -I. -I/usr/local/openssl/include -I/usr/local/include   -c -o danetls-getdns.o danetls-getdns.c
cc -g -Wall -Wextra -I. -I/usr/local/openssl/include -I/usr/local/include   -c -o query-getdns.o query-getdns.c
cc -L/usr/local/openssl/lib -L/usr/local/lib -Wl,-rpath -Wl,/usr/local/openssl/lib -Wl,-rpath -Wl,/usr/local/lib -o danetls-getdns danetls-getdns.o query-getdns.o utils.o tls.o starttls.o tlsardata.o -lssl -lcrypto -lldns -lgetdns_ext_event -lgetdns -levent_core -lunbound -lidn
/usr/bin/ld: cannot find -lgetdns_ext_event
collect2: error: ld returned 1 exit status
make: *** [Makefile:30: danetls-getdns] Error 1

It's possible that this has something to do with:
getdnsapi/getdns#470

Could you please check?