Fix a crash when running viking village using forward clustered renderer, and set shaders to 4.5 so they work on Mac OS

Assets/ScriptableRenderLoop/fptl/FptlLighting.cs

 
             if (enableClustered)
             {
-                s_GlobalLightListAtomic.Release();
+				if (s_GlobalLightListAtomic != null)
+                	s_GlobalLightListAtomic.Release();
             }
 
             ClearComputeBuffers();

Assets/ScriptableRenderLoop/fptl/Internal-DeferredReflections.shader

 
 
 CGPROGRAM
-#pragma target 5.0
+#pragma target 4.5
 #pragma vertex vert
 #pragma fragment frag
 

Assets/ScriptableRenderLoop/fptl/Internal-DeferredShading.shader

 
 
 CGPROGRAM
-#pragma target 5.0
+#pragma target 4.5
 #pragma vertex vert
 #pragma fragment frag