Patch provided by Aleksey Cheusov in PR 42195.
Changes:
FIX: POSIX getopt("xo:") accepts './app -xoVVV' and './app -xo VVV'
treating them as './app -x -o VVV'.
Now Lua alt_getopt does the same.
Additional regression tests/examples
error() function is not used for exiting anymore.
os.exit() is used instead.
lua_altgetopt is a module for Lua programming language
for processing application's arguments the same way
BSD/GNU getopt_long(3) functions do.
Main features and goals:
1) compatibility to SUS "Utility Syntax Guidelines"
http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap12.html#tag_12_02
guidelines 3-13.
2) This module is for plain Lua
2) No extra dependencies
3) No hooks, no functional tricks ;-)
4) Support for long options, e.g. compatibility with getopt_long(3) C
function
present in *BSD and GNU libc.
5) Long options may optionally have one-char synonym or other long synonym
6) Strict error checking (checks for an incorrect use of options)
7) alt_getopt.lua is a Lua module.
