Fixed compiling test program with Emscripten.
diff --git a/test/testgles2.c b/test/testgles2.c
index fedf311..55f06cb 100644
--- a/test/testgles2.c
+++ b/test/testgles2.c
@@ -20,7 +20,7 @@
#include "SDL_test_common.h"
-#if defined(__IPHONEOS__) || defined(__ANDROID__) || defined(__NACL__)
+#if defined(__IPHONEOS__) || defined(__ANDROID__) || defined(__EMSCRIPTEN__) || defined(__NACL__)
#define HAVE_OPENGLES2
#endif