Revert "headers: Add various missing G_DISABLE_DEPRECATED guards"
This reverts commit 80fcb1bc. G_DISABLE_DEPRECATED should never be used by anybody, least of all by GLib. We have deprecation annotations for the compiler, these days, and they are much better suited than a macro that makes symbols appear and disappear. The fact that gtk-doc doesn't understand the deprecation annotations is a limitation of gtk-doc, and it's gtk-doc that ought to be fixed. Commit 80fcb1bc broke GStreamer, which disables old API that was deprecated before the introduction of the deprecation annotations, but still uses newly deprecated one, and relies on the deprecation annotations to do their thing. It also broke libsoup, as it uses GValueArray in its own API.