unity burst

报错

BuildFailedException: Burst compiler (1.1.2) failed running

stdout:
Burst requires the android NDK to be correctly installed (it can be installed via the unity installer add component) in order to build a standalone player for Android with ARMV7A_NEON32
The environment variable ANDROID_NDK_ROOT is undefined or empty, is the Android NDK correctly installed?
stderr:

Unity.Burst.Editor.BurstAotCompiler+BclRunner.RunProgram (UnityEditor.Utils.Program p, System.String exe, System.String args, System.String workingDirectory, UnityEditor.Scripting.Compilers.CompilerOutputParserBase parser, UnityEditor.Build.Reporting.BuildReport report) (at Library/PackageCache/com.unity.burst@1.1.2/Editor/BurstAotCompiler.cs:659)
Unity.Burst.Editor.BurstAotCompiler+BclRunner.RunManagedProgram (System.String exe, System.String args, System.String workingDirectory, UnityEditor.Scripting.Compilers.CompilerOutputParserBase parser, UnityEditor.Build.Reporting.BuildReport report) (at Library/PackageCache/com.unity.burst@1.1.2/Editor/BurstAotCompiler.cs:597)
Unity.Burst.Editor.BurstAotCompiler+BclRunner.RunManagedProgram (System.String exe, System.String args, UnityEditor.Scripting.Compilers.CompilerOutputParserBase parser, UnityEditor.Build.Reporting.BuildReport report) (at Library/PackageCache/com.unity.burst@1.1.2/Editor/BurstAotCompiler.cs:571)
Unity.Burst.Editor.BurstAotCompiler.OnPostBuildPlayerScriptDLLsImpl (UnityEditor.Build.Reporting.BuildReport report) (at Library/PackageCache/com.unity.burst@1.1.2/Editor/BurstAotCompiler.cs:286)
Unity.Burst.Editor.BurstAotCompiler.OnPostBuildPlayerScriptDLLs (UnityEditor.Build.Reporting.BuildReport report) (at Library/PackageCache/com.unity.burst@1.1.2/Editor/BurstAotCompiler.cs:46)
UnityEditor.Build.BuildPipelineInterfaces.OnPostBuildPlayerScriptDLLs (UnityEditor.Build.Reporting.BuildReport report) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/BuildPipelineInterfaces.cs:452)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr) (at C:/buildslave/unity/build/Modules/IMGUI/GUIUtility.cs:179)

https://forum.unity.com/threads/burst-failes-to-compile-for-android.660394/
放到打包工程

#if UNITY_EDITOR
using UnityEditor;
using UnityEditor.Build;
using UnityEditor.Build.Reporting;
using System;

public class FixBurstCompiler : IPreprocessBuildWithReport
{
    public int callbackOrder { get { return 0; } }

    public void OnPreprocessBuild(BuildReport report)
    {
#if UNITY_2018_4
        var ndkRoot = EditorPrefs.GetString("AndroidNdkRootR16b");

        Environment.SetEnvironmentVariable("ANDROID_NDK_ROOT", ndkRoot);
#endif
    }
}
#endif