fuzzing: Enable espeak deterministic mode (#2078)

tests/fuzzing/synth_fuzzer.c

@@ -49,6 +49,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
 	{
 		int options = espeakINITIALIZE_DONT_EXIT;
 		espeak_Initialize(AUDIO_OUTPUT_SYNCHRONOUS, buflength, PATH_ESPEAK_DATA, options);
+		espeak_ng_SetRandSeed(1);
 		espeak_SetSynthCallback(espeak_callback);
 		const char *lang = getenv("FUZZ_VOICE");
 		if (lang == NULL)

tests/ssml-fuzzer.c

@@ -55,6 +55,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
 			setenv("ESPEAK_DATA_PATH",filepath,0);
 		}
 		espeak_Initialize(AUDIO_OUTPUT_SYNCHRONOUS, 0, NULL, 0);
+		espeak_ng_SetRandSeed(1);
 		espeak_SetSynthCallback(SynthCallback);
 		initialized = 1;
 	}