Fixed shadowmap sampling out of borders by taking z direction into account.

ScriptableRenderPipeline/LightweightPipeline/LWRP/ShaderLibrary/Shadows.hlsl

 float4      _FrustumCorners[4];
 CBUFFER_END
 
+#if UNITY_REVERSED_Z
+#define BEYOND_SHADOW_FAR(shadowCoord) shadowCoord.z <= UNITY_RAW_FAR_CLIP_VALUE
+#else
+#define BEYOND_SHADOW_FAR(shadowCoord) shadowCoord.z >= UNITY_RAW_FAR_CLIP_VALUE
+#endif
+
+#define OUTSIDE_SHADOW_BOUNDS(shadowCoord) shadowCoord.x <= 0 || shadowCoord.x >= 1 || shadowCoord.y <= 0 || shadowCoord.y >= 1 || BEYOND_SHADOW_FAR(shadowCoord)
+
 half GetShadowStrength()
 {
     return _ShadowData.x;
 #endif
 
     // Shadow coords that fall out of the light frustum volume must always return attenuation 1.0
-    // TODO: We can set shadowmap sampler to clamptoborder when we don't have a shadow atlas and avoid xy coord bounds check
-    return (shadowCoord.x <= 0 || shadowCoord.x >= 1 || shadowCoord.y <= 0 || shadowCoord.y >= 1 || shadowCoord.z >= 1) ? 1.0 : attenuation;
+    return (OUTSIDE_SHADOW_BOUNDS(shadowCoord)) ? 1.0 : attenuation;
 }
 
 inline half ComputeCascadeIndex(float3 positionWS)