Fix clang -Wconditional-uninitialized warnings.

src/libespeak-ng/compiledata.c

@@ -2792,7 +2792,7 @@ espeak_ng_STATUS espeak_ng_CompileIntonation(FILE *log)
 	char c;
 	int keyword;
 	int n_tune_names = 0;
-	int done_split;
+	int done_split = 0;
 	int done_onset = 0;
 	int done_last = 0;
 	int n_preset_tunes = 0;

src/libespeak-ng/translate.c

@@ -2188,7 +2188,7 @@ void *TranslateClause(Translator *tr, FILE *f_text, const void *vp_input, int *t
 {
 	int ix;
 	int c;
-	int cc;
+	int cc = 0;
 	unsigned int source_index = 0;
 	unsigned int prev_source_index = 0;
 	int source_index_word = 0;

src/libespeak-ng/wavegen.c

@@ -980,7 +980,7 @@ int Wavegen()
 	signed char c;
 	int sample;
 	int amp;
-	int modn_amp, modn_period;
+	int modn_amp = 1, modn_period;
 	static int agc = 256;
 	static int h_switch_sign = 0;
 	static int cycle_count = 0;