Squashed 'external/SDL/' content from commit 716c767b7

git-subtree-dir: external/SDL
git-subtree-split: 716c767b7e7099fb0e2fda9db59227a7e1d1d8a4

test/testgpu/overlay.frag.hlsl

@@ -0,0 +1,10 @@
+
+#include "overlay.hlsli"
+
+Texture2D<float4> t0 : register(t0, space2);
+SamplerState s0 : register(s0, space2);
+
+float4 main(VSOutput input) : SV_Target0
+{
+    return t0.Sample(s0, input.uv);
+}