tray: Don't try to use GTK 2 versions of libappindicator

We use GTK 3 functions in this file, so we cannot load a libappindicator
whose SONAME indicates that it is using GTK 2.

Signed-off-by: Simon McVittie <smcv@collabora.com>

src/tray/unix/SDL_tray.c

@@ -176,11 +176,8 @@ static void quit_gtk(void)
 const char *appindicator_names[] = {
     "libayatana-appindicator3.so",
     "libayatana-appindicator3.so.1",
-    "libayatana-appindicator.so",
     "libappindicator3.so",
     "libappindicator3.so.1",
-    "libappindicator.so",
-    "libappindicator.so.1",
     NULL
 };