SDL: Fixed emscripten build

From 91b328c2c6ce92cf255f68a85bd5de14dee00e07 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Wed, 8 Mar 2023 08:58:26 -0800
Subject: [PATCH] Fixed emscripten build

---
 test/testgles2.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/test/testgles2.c b/test/testgles2.c
index a4cc341494a3..d57864e9918b 100644
--- a/test/testgles2.c
+++ b/test/testgles2.c
@@ -522,7 +522,9 @@ Render(unsigned int width, unsigned int height, shader_data *data)
 static int done;
 static Uint32 frames;
 static shader_data *datas;
+#ifndef __EMSCRIPTEN__
 static thread_data *threads;
+#endif
 
 static void
 render_window(int index)