PBR shader gbuffer ztest (#43)

* Fixed PBR shader rendering in deferred

* Updated changelog

Author: Antoine Lelievre

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -544,6 +544,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed an issue that was collapsing the volume components in the HDRP default settings
 - Fixed warning about missing bound decal buffer
 - Fixed shader warning on Xbox for ResolveStencilBuffer.compute. 
+- Fixed PBR shader ZTest rendering in deferred.
 
 ### Changed
 - Color buffer pyramid is not allocated anymore if neither refraction nor distortion are enabled

com.unity.render-pipelines.high-definition/Editor/Material/PBR/ShaderGraph/PBRSubTarget.cs

@@ -277,7 +277,8 @@ static class PBRRenderStates
             public static RenderStateCollection GBuffer = new RenderStateCollection
             {
                 { RenderState.Cull(Cull.Off), new FieldCondition(Fields.DoubleSided, true) },
-                { RenderState.ZTest(CoreRenderStates.Uniforms.zTestGBuffer) },
+                { RenderState.ZTest(ZTest.Equal), new FieldCondition(Fields.AlphaClip, true) },
+                { RenderState.ZTest(ZTest.LEqual), new FieldCondition(Fields.AlphaClip, false) },
                 { RenderState.Stencil(new StencilDescriptor()
                 {
                     WriteMask = $"{ 0 | (int)StencilUsage.RequiresDeferredLighting | (int)StencilUsage.SubsurfaceScattering | (int)StencilUsage.TraceReflectionRay}",