add basic fuzzers (#348)

* add basic fuzzing using libFuzzer

* let cmake respect cflags, otherwise the fuzzer flags go unnoticed

also, integrates badly with oss-fuzz

* add new fuzzer for minification, simplify the old one

* add fuzzer for the dump example

* clang format

fuzz/fuzz_parser.cpp

@@ -0,0 +1,10 @@
+#include "simdjson/jsonparser.h"
+#include <cstddef>
+#include <cstdint>
+#include <string>
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+
+  auto ignored = simdjson::build_parsed_json(Data, Size);
+
+  return 0;
+}