splayer: fix memory leak on espeak terminate

src/libespeak-ng/sPlayer.c

 }
 
 void KlattFiniSP() {
-	speechPlayer_terminate(speechPlayerHandle);
+	if (speechPlayerHandle)
+		speechPlayer_terminate(speechPlayerHandle);
+	speechPlayerHandle = NULL;
 }
 
 void KlattResetSP() {

src/libespeak-ng/speech.c

 		p_decoder = NULL;
 	}
 
+	WavegenFini();
+
 	return ENS_OK;
 }