Use the following configure command:
$ ./configure --with-fuzzer --with-fuzzer-lib=/path/to/libFuzzer.a \
CC=clang CXX=clang++
Places an irssi-fuzz in src/fe-fuzz/ after build.
Also can specify SANFLAGS to override the chosen sanitizer flags
(defaults to "-g -fsanitize=address -fsanitize-coverage=trace-pc-guard").
