Exposes a dummy version of set_allow_pipewire in case the library is built
without WEBRTC_USE_PIPEWIRE. This function is expected to be used by
applications, and removing it completely breaks the ABI.

--- tg_owt-91d836dc84a16584c6ac52b36c04c0de504d9c34.orig/src/modules/desktop_capture/desktop_capture_options.h
+++ tg_owt-91d836dc84a16584c6ac52b36c04c0de504d9c34/src/modules/desktop_capture/desktop_capture_options.h
@@ -131,6 +131,9 @@
 #if defined(WEBRTC_USE_PIPEWIRE)
   bool allow_pipewire() const { return allow_pipewire_; }
   void set_allow_pipewire(bool allow) { allow_pipewire_ = allow; }
+#else
+  bool allow_pipewire() const { return false; }
+  void set_allow_pipewire(bool allow) { }
 #endif
 
  private: