BUG #16304: ECPG won't accept input from STDIN

The following bug has been logged on the website:

Bug reference: 16304
Logged by: James Gray
Email address: jim_gray(at)cox(dot)net
PostgreSQL version: 11.5
Operating system: AIX
Description:

On an older version (9.6.3) of Postgres on CentOS 7.7.1908, ECPG accepts
input from STDIN:

[singha7] (jgray) ~> psql --version
psql (PostgreSQL) 9.6.3
[singha7] (jgray) ~>

[singha7] (jgray) ~> ecpg -o - -
/* Processed by ecpg (4.12.0) */
/* These include files are added by the preprocessor */
#include <ecpglib.h>
#include <ecpgerrno.h>
#include <sqlca.h>
/* End of automatic include section */

#line 1 "stdin"
^C
[singha7] (jgray) ~>

On a newer version (11.5) of Postgres on AIX 7.2, ECPG does NOT accept input
from STDIN:

bash-5.0$ psql --version
psql (PostgreSQL) 11.5
bash-5.0$

bash-5.0$ ecpg -o - -
Try "ecpg --help" for more information.
bash-5.0$

I suspect a problem in the Postgres version of getopt_long.c