package/gconf: remove package, broken

gconf has not seen any release since 2013, and the last commit in
https://gitlab.gnome.org/Archive/gconf is from 2015.

The package example application basic-gconf-app fails to build with a
recent compiler such as GCC 14.x:

basic-gconf-app.c:458:60: error: passing argument 1 of ‘gtk_dialog_get_content_area’ from incompatible pointer type [-Wincompatible-pointer-types]

It is not entirely clear since when this breakage takes place, but
most likely since GCC 14.x was introduced. This issue can be
reproduced including on 2025.02.x with the following defconfig:

BR2_aarch64=y
BR2_TOOLCHAIN_EXTERNAL=y
BR2_TOOLCHAIN_EXTERNAL_BOOTLIN=y
BR2_PACKAGE_MESA3D=y
BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_SWRAST=y
BR2_PACKAGE_MESA3D_OPENGL_EGL=y
BR2_PACKAGE_MESA3D_OPENGL_ES=y
BR2_PACKAGE_LIBGTK3=y
BR2_PACKAGE_GCONF=y

However, for the build issue to happen you need to run:

$ make libgtk3
$ make

So that libgtk3 gets built before gconf. Indeed, there's a hidden
dependency between the two, and the example programs of gconf only get
build if libgtk3 is built before. We've however encountered the
problem in a (real) bigger build where the dependency relationship of
packages have caused libgtk3 to get built before gconf.

Note that we could perhaps have fixed the problem by disabling the
examples, but gconf is anyway so old and deprecated that it isn't
worth the effort.

There are no known autobuilder issues.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

Config.in.legacy

@@ -146,6 +146,13 @@ endif
 
 comment "Legacy options removed in 2026.02"
 
+config BR2_PACKAGE_GCONF
+	bool "gconf package removed"
+	select BR2_LEGACY
+	help
+	  gconf was no longer maintained upstream, so it has been
+	  dropped.
+
 config BR2_PACKAGE_LIBSVG
 	bool "libsvg package removed"
 	select BR2_LEGACY