Meta: Return 0 from the fuzzing function in most cases

LibFuzzer documentation [1] states that all return values except for 0
and -1 are currently reserved for future use. -1 is a special return
value that causes LibFuzzer to not add a testing input to the testing
corpus, regardless of the code coverage that it causes.

[1] https://llvm.org/docs/LibFuzzer.html

Meta/Lagom/Fuzzers/FuzzMP3Loader.cpp

@@ -21,7 +21,7 @@ extern "C" int LLVMFuzzerTestOneInput(uint8_t const* data, size_t size)
     for (;;) {
         auto samples = mp3->get_more_samples();
         if (samples.is_error())
-            return 2;
+            return 0;
         if (samples.value().size() > 0)
             break;
     }