SpeechSynthesis.java: Simplify the SetVoiceByProperties parameters.

The `age` parameter is not useful as eSpeak does not use this when
selecting voices. This is always set to `0` by TtsService.java.

The `variant` parameter is not used to select the actual voice
variant (from the `!v` directory) but to select the n^th matching
voice from the list of matching voices. This is always set to
select the first matching voice by TtsService.java.

android/jni/jni/eSpeakService.cpp

 
 JNIEXPORT jboolean
 JNICALL Java_com_reecedunn_espeak_SpeechSynthesis_nativeSetVoiceByProperties(
-    JNIEnv *env, jobject object, jstring name, jstring languages, jint gender, jint age,
-    jint variant) {
+    JNIEnv *env, jobject object, jstring name, jstring languages, jint gender) {
   const char *c_name = name ? env->GetStringUTFChars(name, NULL) : NULL;
   const char *c_languages = languages ? env->GetStringUTFChars(languages, NULL) : NULL;
 
 
   voice_select.name = c_name;
   voice_select.languages = c_languages;
-  voice_select.age = (int) age;
   voice_select.gender = (int) gender;
-  voice_select.variant = (int) variant;
 
   const espeak_ERROR result = espeak_SetVoiceByProperties(&voice_select);
 

android/src/com/reecedunn/espeak/SpeechSynthesis.java

         return voices;
     }
 
-    public void setVoiceByProperties(
-            String name, String languages, int gender, int age, int variant) {
-        nativeSetVoiceByProperties(name, languages, gender, age, variant);
+    public void setVoiceByProperties(String name, String languages, int gender) {
+        nativeSetVoiceByProperties(name, languages, gender);
     }
 
     public void setRate(int rate) {
 
     private native final String[] nativeGetAvailableVoices();
 
-    private native final boolean nativeSetVoiceByProperties(
-            String name, String languages, int gender, int age, int variant);
+    private native final boolean nativeSetVoiceByProperties(String name, String languages, int gender);
 
     private native final boolean nativeSetRate(int rate);
 

android/src/com/reecedunn/espeak/TtsService.java

         mCallback.start(mEngine.getSampleRate(), mEngine.getAudioFormat(),
                 mEngine.getChannelCount());
 
-        mEngine.setVoiceByProperties(null, mMatchingVoice.name, gender, 0, 0);
+        mEngine.setVoiceByProperties(null, mMatchingVoice.name, gender);
         mEngine.setRate(rate);
         mEngine.setPitch(pitch);
         mEngine.synthesize(text, text.startsWith("<speak"));