Add basic fuzzing build tasks config.nims file

tests/fuzzing/config.nims

@@ -0,0 +1,30 @@
+proc aflSwitches() =
+  switch("define", "afl")
+  switch("define", "noSignalHandler")
+  switch("cc", "gcc")
+  switch("gcc.exe", "afl-gcc")
+  switch("gcc.linkerexe", "afl-gcc")
+  switch("out", "fuzz-afl")
+
+proc libFuzzerSwitches() =
+  switch("noMain", "")
+  switch("cc", "clang")
+  switch("passC", "-fsanitize=fuzzer,address")
+  switch("passL", "-fsanitize=fuzzer,address")
+  switch("out", "fuzz-libfuzzer")
+
+proc generalSwitches() =
+  switch("verbosity", "0")
+  switch("hints", "off")
+  switch("warnings", "off")
+  switch("define", "chronicles_log_level:fatal")
+
+task build_afl, "Build for afl fuzzing":
+  aflSwitches()
+  generalSwitches()
+  setCommand("c")
+
+task build_libfuzzer, "Build for libFuzzer fuzzing":
+  libFuzzerSwitches()
+  generalSwitches()
+  setCommand("c")