tray: Load GTK and libappindicator by versioned names, except on OpenBSD

We are expecting a specific ABI (we can see that from the declarations
listed in this file) and the whole point of SONAME versioning is to
say that the library conforms to a specific ABI. If the SONAME is not
the one we expect, then calling its functions is likely to crash.

As usual, an exception to this is that OpenBSD does not use SONAME
versioning.

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

src/tray/unix/SDL_tray.c

@@ -174,22 +174,31 @@ static void quit_gtk(void)
 }
 
 const char *appindicator_names[] = {
+#ifdef SDL_PLATFORM_OPENBSD
     "libayatana-appindicator3.so",
-    "libayatana-appindicator3.so.1",
     "libappindicator3.so",
+#else
+    "libayatana-appindicator3.so.1",
     "libappindicator3.so.1",
+#endif
     NULL
 };
 
 const char *gtk_names[] = {
+#ifdef SDL_PLATFORM_OPENBSD
     "libgtk-3.so",
+#else
     "libgtk-3.so.0",
+#endif
     NULL
 };
 
 const char *gdk_names[] = {
+#ifdef SDL_PLATFORM_OPENBSD
     "libgdk-3.so",
+#else
     "libgdk-3.so.0",
+#endif
     NULL
 };