Add fuzz testing corpus and build

Makefile

@@ -1,4 +1,7 @@
 
+AFL_CC ?= afl-clang-fast
+AFL_CXX ?= afl-clang-fast++
+
 .PHONY: all coverage coverage_report install uninstall
 
 all: wl
@@ -19,6 +22,19 @@ coverage_report:
 	lcov --remove coverage.info '/usr/*' --output-file coverage_filtered.info
 	genhtml coverage_filtered.info --output-directory coverage_html --title "WL Template Engine Coverage"
 
+fuzz: fuzz.c wl.c wl.h
+	$(AFL_CC) fuzz.c wl.c -o fuzz \
+		-g -O3 -Wall \
+		-fsanitize=address,undefined \
+		-fno-omit-frame-pointer
+
+bugs: fuzz
+	AFL_SKIP_CPUFREQ=1 afl-fuzz \
+	-i fuzz_input \
+	-o /tmp/fuzz_output \
+	-m none \
+	./fuzz
+
 install: wl
 	sudo cp wl /usr/local/bin