Force GTK file chooser only in the official builds.

Telegram/SourceFiles/platform/linux/file_utilities_linux.cpp

@@ -100,6 +100,9 @@ using Type = ::FileDialog::internal::Type;
 
 #ifndef TDESKTOP_DISABLE_GTK_INTEGRATION
 bool NativeSupported() {
+#ifndef TDESKTOP_FORCE_GTK_FILE_DIALOG
+	return false;
+#endif // TDESKTOP_FORCE_GTK_FILE_DIALOG
 	return Platform::internal::GdkHelperLoaded()
 		&& (Libs::gtk_widget_hide_on_delete != nullptr)
 		&& (Libs::gtk_clipboard_store != nullptr)

Telegram/gyp/Telegram.gyp

@@ -130,6 +130,7 @@
       [ '"<(official_build_target)" != ""', {
         'defines': [
           'TDESKTOP_OFFICIAL_TARGET=<(official_build_target)',
+          'TDESKTOP_FORCE_GTK_FILE_DIALOG',
         ],
         'dependencies': [
           'utils.gyp:Packer',