Fix changing mbrola voices in ssml (#1997)

This fixes #1011 by integrating mbrola voices details in ssml processing

src/libespeak-ng/readclause.c

 					xml_buf[n_xml_buf] = 0;
 					c2 = ' ';
 
+					if (base_voice.identifier)
+						strcpy(current_voice_id, base_voice.identifier);
 					terminator = ProcessSsmlTag(xml_buf, buf, &ix, n_buf, xmlbase, &audio_text, current_voice_id, &base_voice, base_voice_variant_name, &ignore_text, &clear_skipping_text, &sayas_mode, &sayas_start, ssml_stack, &n_ssml_stack, &n_param_stack, (int *)speech_parameters);
 
 					if (terminator != 0) {

src/libespeak-ng/ssml.c

 	int voice_found;
 	espeak_VOICE voice_select;
 	static char voice_name[40];
+	static char identifier[40];
 	char language[40];
 
 	MAKE_MEM_UNDEFINED(&voice_name, sizeof(voice_name));
 	voice_select.identifier = NULL;
 
 	for (ix = 0; ix < n_ssml_stack; ix++) {
+		espeak_VOICE *v;
 		sp = &ssml_stack[ix];
 		int voice_name_specified = 0;
 
-		if ((sp->voice_name[0] != 0) && (SelectVoiceByName(NULL, sp->voice_name) != NULL)) {
+		if ((sp->voice_name[0] != 0) && ((v = SelectVoiceByName(NULL, sp->voice_name)) != NULL)) {
 			voice_name_specified = 1;
 			strcpy(voice_name, sp->voice_name);
+			strcpy(identifier, v->identifier);
 			language[0] = 0;
 			voice_select.gender = ENGENDER_UNKNOWN;
 			voice_select.age = 0;
 			}
 
 			if (voice_name_specified == 0)
+			{
 				voice_name[0] = 0; // forget a previous voice name if a language is specified
+				identifier[0] = 0;
+			}
 		}
 		if (sp->voice_gender != ENGENDER_UNKNOWN)
 			voice_select.gender = sp->voice_gender;
 	}
 
 	voice_select.name = voice_name;
+	voice_select.identifier = identifier;
 	voice_select.languages = language;
+
 	v_id = SelectVoice(&voice_select, &voice_found);
 	if (v_id == NULL)
 		return "default";

src/libespeak-ng/voices.c

 	}
 
 	// select and sort voices for the required language
-	nv = SetVoiceScores(&voice_select2, voices, 0);
+	nv = SetVoiceScores(&voice_select2, voices,
+			voice_select2.identifier && strncmp(voice_select2.identifier, "mb/", 3) == 0 ? 1 : 0);
 
 	if (nv == 0) {
 		// no matching voice, choose the default

tests/ssml/external-entity.expected

 
-
 hˈɪɹ ɑː͡ɹ ðə pˈæswɜːdz
 
 

tests/ssml/spec-example-1.expected

 
 
-
 juː hæv fˈɔː͡ɹ nˈuː mˈɛsɪd͡ʒᵻz
 
 ðə fˈɜːst ɪz fɹʌm stˈɛfəni wˈɪljəmz ænd ɚɹˈa͡ɪvd æt