JNI_Unload must return the JNI version needed by the native library

src/core/SDL_core_unsupported.c

@@ -184,7 +184,6 @@ Sint32 JNI_OnLoad(JavaVM *vm, void *reserved)
 {
     (void)vm;
     (void)reserved;
-    SDL_Unsupported();
+    return 0x00010004; // JNI_VERSION_1_4
-    return -1; // JNI_ERR
 }
 #endif