[FS#1454] argp-standalone: option ARGP_NO_ERRS is not honoured

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Othmar Truniger (tru7) 

Attached to Project - OpenWrt/LEDE Project
Summary - argp-standalone: option ARGP_NO_ERRS is not honoured
Task Type - Bug Report
Category - Packages
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Symptom: error message is written for invalid option even with ARGP_NO_ERRS set in function argp_parse
   
Verified on ar71xx / mips_24kc / wndr3700 and mpc85xx / powerpc_8540 / tl-wdr4900
OpenWrt / LEDE trunk  OpenWrt SNAPSHOT, r6548-8e1065d681

Found a problem when working with a software project where the LEDE / OpenWrt binary issues an error message for an invalid option when starting the binary while the debian / ubuntu linux version does not. I tracked it down to the fact that it must be a bug in the argp-standalone library of OpenWrt / LEDE where the option ARGP_NO_ERRS in function argp_parse is not honoured. 

To reproduce I wrote a little demo program which works fine on debian and ubuntu but shows the invalid behaviour on OpenWrt / LEDE.

The demo program is hosted on https://github.com/tru7/argp-demo where I have also provided a feed named Makefile.lede to build the package on OpenWrt / LEDE.

I have no skills in coding and absolutely no skills in debugging, so this is about all I can do about this.

More information can be found at the following URL:
https://bugs.openwrt.org/index.php?do=details&task_id=1454