pkg/59556: libpkgconf/pkg.c:101:37: error: 'O_DIRECTORY' undeclared on SCO/Xinuos UnixWare 7 Definitive 2018 MP1

[gavrilovegor519%gmail.com@localhost]

>Number:         59556
>Category:       pkg
>Synopsis:       libpkgconf/pkg.c:101:37: error: 'O_DIRECTORY' undeclared on SCO/Xinuos UnixWare 7 Definitive 2018 MP1
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Jul 25 16:25:00 +0000 2025
>Originator:     Egor
>Release:        both - stable (2025Q2) and latest (25 July 2025)
>Organization:
>Environment:
UnixWare uw7 5 7.1.4 i386 x86at SCO UNIX_SVR5
>Description:
Here logs about this bug:

```
UX:rm: ERROR: Cannot access libtoolT: No such file or directory
=> Modifying libtool scripts to use pkgsrc libtool
=> Modifying libtool scripts to use pkgsrc depcomp
===> Building for pkgconf-2.4.3nb1
  CC       cli/pkgconf-main.o
  CC       cli/pkgconf-getopt_long.o
  CC       cli/pkgconf-renderer-msvc.o
  CC       libpkgconf/audit.lo
  CC       libpkgconf/buffer.lo
  CC       libpkgconf/cache.lo
  CC       libpkgconf/client.lo
  CC       libpkgconf/pkg.lo
libpkgconf/pkg.c: In function 'pkg_get_parent_dir':
libpkgconf/pkg.c:101:37: error: 'O_DIRECTORY' undeclared (first use in this function); did you mean '_DIRENT_H'?
   const int dirfd = open(targetdir, O_DIRECTORY);
                                     ^~~~~~~~~~~
                                     _DIRENT_H
libpkgconf/pkg.c:101:37: note: each undeclared identifier is reported only once for each function it appears in
libpkgconf/pkg.c:106:17: warning: implicit declaration of function 'readlinkat'; did you mean 'readlink'? [-Wimplicit-function-declaration]
   ssize_t len = readlinkat(dirfd, targetfilename, sourcebuf, sizeof(sourcebuf) - 1);
                 ^~~~~~~~~~
                 readlink
*** Error code 1

Stop.
```

Not buildings all FF-based browsers - Firefox 52, Palemoon, Seamonkey, and more.
>How-To-Repeat:
Build Firefox 52, Palemoon, or Seamonkey on machine with one of SCO's UNIXes.
>Fix:
Block build this packages in UnixWare, because this system not support modern POSIX standarts - only UNIX95. More info: https://stackoverflow.com/a/53693451