code cleanup: remove unused language option l_length_mods.

It is not used by any language. There is no need to check for it in
LoadVoice().

CHANGELOG.md

 *  Add support for speechPlayer.
 *  Add more tests to check the various parts of espeak-ng.
 *  Various changes to clean up the codebase (Juho Hiltunen)
+*  Remove support for l_length_mods language option
 *  Restructure "option brackets" language option to "brackets" and "bracketsAnnounced".
 *  Restructure "stressLength" and "stressAdd" language option
 *  New Language option: "lowercaseSentence" for ending a sentence if a period is followed by a lower case letter.

src/libespeak-ng/translate.h

 // 0=default, 1=no check, other allow this character as an extra initial letter (default is 's')
 #define LOPT_UNPRONOUNCABLE 5
 
-// select length_mods tables,  (length_mod_tab) + (length_mod_tab0 * 100)
-#define LOPT_LENGTH_MODS 6
-
 // increase this to prevent sonorants being shortened before shortened (eg. unstressed) vowels
 #define LOPT_SONORANT_MIN 7
 

src/libespeak-ng/voices.c

 #include "dictionary.h"               // for strncpy0, LoadDictionary
 #include "mnemonics.h"               // for LookupMnemName, MNEM_TAB
 #include "phoneme.h"                  // for REPLACE_PHONEMES, n_replace_pho...
-#include "setlengths.h"          // for SetLengthMods
 #include "speech.h"                   // for GetFileLength, PATHSEP
 #include "mbrola.h"                   // for LoadMbrolaTable
 #include "synthdata.h"                // for SelectPhonemeTableName, LookupP...
 	{ "l_regressive_v",   0x100+LOPT_REGRESSIVE_VOICING },
 	{ "l_unpronouncable", 0x100+LOPT_UNPRONOUNCABLE },
 	{ "l_sonorant_min",   0x100+LOPT_SONORANT_MIN },
-	{ "l_length_mods",    0x100+LOPT_LENGTH_MODS },
 	{ "apostrophe",       0x100+LOPT_APOSTROPHE },
 	{ "brackets",       0x100+LOPT_BRACKET_PAUSE },
 	{ "bracketsAnnounced",       0x100+LOPT_BRACKET_PAUSE_ANNOUNCED },
 		voice_languages[langix] = 0;
 	}
 
-	if ((value = translator->langopts.param[LOPT_LENGTH_MODS]) != 0)
-		SetLengthMods(translator, value);
-
 	voice->width[0] = (voice->width[0] * 105)/100;
 
 	return voice;