Merge pull request #1009 from Unity-Technologies/LW-gles2-fix

Added 'prefer_hlslcc' directive

ScriptableRenderPipeline/LightweightPipeline/LWRP/Shaders/LightweightScreenSpaceShadows.shader

 
         HLSLINCLUDE
 
+        #pragma prefer_hlslcc gles
         //Keep compiler quiet about Shadows.hlsl. 
         #include "CoreRP/ShaderLibrary/Common.hlsl"
         #include "CoreRP/ShaderLibrary/EntityLighting.hlsl"