glib-backports: Remove obsoleted backports

They're not necessary now that we depend on GLib >= 2.72

src/glib-backports.h

@@ -70,21 +70,3 @@ _g_clear_fd_ignore_error (int *fd_ptr)
 
 #define g_autofd __attribute__((cleanup(_g_clear_fd_ignore_error)))
 #endif
-
-#if !GLIB_CHECK_VERSION (2, 68, 0)
-guint g_string_replace (GString     *string,
-                        const gchar *find,
-                        const gchar *replace,
-                        guint        limit);
-#endif
-
-#if !GLIB_CHECK_VERSION (2, 68, 0)
-static inline void
-g_log_writer_default_set_use_stderr (gboolean use_stderr)
-{
-  /* Does nothing because outside of the tests we don't really care that it
-   * doesn't work correctly after this call and those tests can run on newer
-   * GLibs
-   */
-}
-#endif

src/meson.build

@@ -77,7 +77,6 @@ xdg_desktop_portal_sources = files(
   'file-chooser.c',
   'flatpak-instance.c',
   'gamemode.c',
-  'glib-backports.c',
   'global-shortcuts.c',
   'inhibit.c',
   'input-capture.c',
@@ -205,7 +204,6 @@ configure_file(
 executable(
   'xdg-desktop-portal-rewrite-launchers',
   'rewrite-launchers.c',
-  'glib-backports.c',
   dependencies: common_deps,
   include_directories: common_includes,
   install: true,