[gegl] meson: GEGL's npd lib is not private and is actually used by software.

[Jehan <jehanp src gnome org>]

commit 05f7eb7107e51291c163880993a4c82cca8bfcd4
Author: Jehan <jehan girinstud io>
Date:   Sat Apr 30 15:30:56 2022 +0200

    meson: GEGL's npd lib is not private and is actually used by software.
    
    Commit be8978bab demoted libgegl-npd to a private library, not caring
    about the fact that this library is actually needed externally. Its API
    is meant to be exposed publically, headers are installed and so on. In
    particular, it is used by GIMP so this commit actually broke GIMP
    builds, as well as our CI.
    
    I can understand that adding this side library this way is not so
    conceptually ideal, so one should be welcome to provide alternatives,
    such as maybe its own pkg-config file, and also changing the API
    namespace to gegl_npd_*() or something like this. But until this is done
    and GIMP code and build at least is ported to such updated API, we
    should not hide away this library meant to be public.

 meson.build | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/meson.build b/meson.build
index 35c3ed702..7688fdcd1 100644
--- a/meson.build
+++ b/meson.build
@@ -510,8 +510,11 @@ pkgconfig.generate(gegl_lib,
   description: 'Generic Graphics Library',
   version: meson.project_version(),
   variables: 'pluginsdir=' + '${prefix}' / get_option('libdir') / api_name,
-  libraries: gegl_pub_deps,
-  libraries_private: gegl_npd_lib,
+  # gegl_npd_lib API is actually used by software, such as GIMP. It must
+  # not be removed, even though adding it like this is not so proper. If
+  # one wants to clean up this dependency, a proper port must be done
+  # first so that using application still build and don't lose features.
+  libraries: gegl_pub_deps + [ gegl_npd_lib ],
   subdirs: api_name,
 )