[Bug-readline] Comment on c612c3607b183ae654d6c920c729de5444fdb899 (commit readline-20190906)

[Osipov, Michael]

Hi Chet,

first of all, thanks for pushing my changes into devel.

I am a bit unhappy with the wording "TGETENT_BROKEN" and "It's not clear 
how HPUX is so broken here." Initially, I shared the same view, but when 
looking into the POSIX definition of tgetent(2) and (tgetflag) by the 
Open Group [1], it says:
> Routines that return an integer return ERR upon failure and an 
integer value other than ERR upon successful completion.

Similar is documented on the manpage [2] for the BSD implementation.

Unfortunately, I cannot find on FreeBSD and HP-UX macros for ERR and OK 
in /usr/include.

For my point of view, HP-UX is not broken, but it simply has another 
internal definition of ERR and OK. One can also invert this 
argumentation and say that GNU termcap or BSD termcap are broken because 
the HP-UX implementation might predate both.

From a technical POV, the code does exactly what is expected now, though.

Regards,

Michael

[1] https://pubs.opengroup.org/onlinepubs/7908799/xcurses/tgetflag.html
[2] 
https://www.freebsd.org/cgi/man.cgi?query=tgetflag&sourceid=opensearch#PORTABILITY