Merge pull request #1407 from Unity-Technologies/remove-UNITY_2018_2_OR_NEWER

Remove UNITY_2018_2_OR_NEWER define (as we are on 2018.2)

com.unity.render-pipelines.core/CoreRP/Textures/TextureCache.cs

                 {
                     case BuildTarget.iOS:
                     case BuildTarget.Android:
-    #if !UNITY_2018_2_OR_NEWER
-                    case BuildTarget.Tizen:
-    #endif
                     case BuildTarget.WSAPlayer:
                         // Note: We return true on purpose even if Windows Store Apps are running on Desktop.
                         return true;

com.unity.render-pipelines.high-definition/HDRP/Debug/DebugDisplay.cs

 
         public void UpdateMaterials()
         {
-#if UNITY_2018_2_OR_NEWER
-#endif
         }
 
         public bool DebugNeedsExposure()

com.unity.render-pipelines.high-definition/HDRP/Editor/BuildPlayer/HDRPVariantStripper.cs

 
 namespace UnityEditor.Experimental.Rendering.HDPipeline
 {
-#if UNITY_2018_2_OR_NEWER
     class HDRPVariantStripper : IPreprocessShaders
     {
         // returns true if the variant should be stripped.
                 inputData.Add(workaround);
         }
     }
-#endif
 }

com.unity.render-pipelines.high-definition/HDRP/Lighting/LightLoop/LightLoop.cs

         {
             m_ShadowMgr.UpdateCullingParameters(ref cullingParams);
             // In HDRP we don't need per object light/probe info so we disable the native code that handles it.
-            #if UNITY_2018_2_OR_NEWER
-            #endif
         }
 
         public bool IsBakedShadowMaskLight(Light light)

com.unity.render-pipelines.lightweight/LWRP/Editor/ShaderPreprocessor.cs

 
 namespace UnityEditor.Experimental.Rendering.LightweightPipeline
 {
-#if UNITY_2018_2_OR_NEWER
     public class ShaderPreprocessor : IPreprocessShaders
     {
 #if LOG_VARIANTS
 #endif
         }
     }
-#endif // UNITY_2018_2_OR_NEWER
 }

com.unity.render-pipelines.lightweight/LWRP/LightweightPipelineCore.cs

         public static readonly string DepthMsaa2 = "_DEPTH_MSAA_2";
         public static readonly string DepthMsaa4 = "_DEPTH_MSAA_4";
 
-#if UNITY_2018_2_OR_NEWER
         public static readonly ShaderKeyword AdditionalLights = new ShaderKeyword(AdditionalLightsText);
         public static readonly ShaderKeyword VertexLights = new ShaderKeyword(VertexLightsText);
         public static readonly ShaderKeyword MixedLightingSubtractive = new ShaderKeyword(MixedLightingSubtractiveText);
 
         public static readonly ShaderKeyword Lightmap = new ShaderKeyword("LIGHTMAP_ON");
         public static readonly ShaderKeyword DirectionalLightmap = new ShaderKeyword("DIRLIGHTMAP_COMBINED");
-#endif
     }
 
     public partial class LightweightPipeline