build: Remove all remaining gtk-doc build infrastructure

It’s no longer needed: the documentation is built by gi-docgen now.

Fixes: #3037

docs/reference/glib/meson.build

@@ -1,100 +1,3 @@
-if get_option('gtk_doc')
-  subdir('xml')
-
-  ignore_headers = [
-    'gallocator.h',
-    'gdatasetprivate.h',
-    'glibintl.h',
-    'gbsearcharray.h',
-    'glib-private.h',
-    'gmoduleconf.h',
-    'grcboxprivate.h',
-    'gstdioprivate.h',
-    'gthreadprivate.h',
-    'gunibreak.h',
-    'gunicomp.h',
-    'gunidecomp.h',
-    'gunichartables.h',
-    'glib_probes.h',
-    'glib_trace.h',
-    'libcharset.h',
-    'gdebug.h',
-    'gprintfint.h',
-    'gmirroringtable.h',
-    'gscripttable.h',
-    'gtrace-private.h',
-    'glib-mirroring-tab',
-    'gnulib',
-    'gbytesprivate.h',
-    'gvariant-internal.h',
-    'gvariant-serialiser.h',
-    'gvariant-core.h',
-    'gvarianttypeinfo.h',
-    'gwakeup.h',
-    'gtranslit-data.h',
-    'glib-init.h',
-    'gconstructor.h',
-    'gconstructorprivate.h',
-    'testutils.h',
-    'valgrind.h',
-    'gutilsprivate.h',
-    'gvalgrind.h',
-    'dirent.h',
-    'glib-unixprivate.h',
-    'glib-visibility.h',
-    'gmodule-visibility.h',
-  ]
-
-  docpath = join_paths(glib_datadir, 'gtk-doc', 'html')
-  version_conf = configuration_data()
-  version_conf.set('GLIB_VERSION', meson.project_version())
-  configure_file(
-    input: 'version.xml.in',
-    output: 'version.xml',
-    configuration: version_conf
-  )
-
-  configure_file(
-    input: 'glib-sections.txt.in',
-    output: 'glib-sections.txt',
-    command: [gen_visibility_macros, meson.project_version(), 'doc-sections', '@INPUT@', '@OUTPUT@'],
-  )
-
-  gnome.gtkdoc('glib',
-               main_xml : 'glib-docs.xml',
-               namespace : 'g',
-               mode : 'none',
-               src_dir : [ 'glib', 'gmodule' ],
-               dependencies : libglib_dep,
-               scan_args : [
-                 '--ignore-decorators=' + ignore_decorators + '|' + ignore_decorators.replace('GLIB', 'GMODULE'),
-                 '--ignore-headers=' + ' '.join(ignore_headers),
-               ],
-               content_files : [
-                 'changes.xml',
-                 'programming.xml',
-                 'resources.xml',
-                 'regex-syntax.xml',
-                 'glib-gettextize.xml',
-                 'gtester.xml',
-                 'gtester-report.xml',
-               ],
-               expand_content_files : [
-               ],
-               html_assets : [
-                 'file-name-encodings.png',
-                 'mainloop-states.gif',
-                 'Sorted_binary_tree_breadth-first_traversal.svg',
-                 'Sorted_binary_tree_inorder.svg',
-                 'Sorted_binary_tree_postorder.svg',
-                 'Sorted_binary_tree_preorder.svg',
-               ],
-               fixxref_args: [
-                 '--html-dir=' + docpath,
-               ],
-               install: true,
-               check: false)
-endif
 
 if get_option('man')
   manpages = ['glib-gettextize', 'gtester', 'gtester-report']
@@ -143,7 +46,6 @@ if get_option('gtk_doc')
   endif
 endif
 
-# gi-docgen version
 expand_content_files = [
   'atomic.md',
   'base64.md',