code cleanup: remove unnecessary current_phoneme_table

The SelectPhonemeTable(voice->phoneme_tab_ix) has no effect for tests.
Passing other values here breaks tests. That means that the relevant
calls SelectPhonemeTable() are already made in other functions.

voice->phoneme_tab_ix is set in LoadVoice().

src/libespeak-ng/synthesize.c

 	return 0; // finished the phoneme list
 }
 
-static int current_phoneme_table;
 int SpeakNextClause(int control)
 {
 	// Speak text from memory (text_in)
 		return 0;
 	}
 
-	if (current_phoneme_table != voice->phoneme_tab_ix)
-		current_phoneme_table = SelectPhonemeTable(voice->phoneme_tab_ix);
-
 	// read the next clause from the input text file, translate it, and generate
 	// entries in the wavegen command queue
 	TranslateClause(translator, &clause_tone, &voice_change);