[MSBuild] Add ApiIntersect keep interop and internal ctor flags

The flags to keep the marshalling/interop information and keep
internal constructors can now be set in the MSBuild project.

Author: mrward

src/Build/NuGet.Build.Packaging.Tasks/ApiIntersect.cs

@@ -19,6 +19,10 @@ public class ApiIntersect : ToolTask
 
 		public ITaskItem[] ExcludeType { get; set; }
 
+		public string KeepInternalConstructors { get; set; }
+
+		public string KeepMarshalling { get; set; }
+
 		[Required]
 		public ITaskItem RootOutputDirectory { get; set; }
 
@@ -74,6 +78,10 @@ protected override string GenerateCommandLineCommands()
 				builder.AppendTextUnquoted("\"");
 			}
 
+			AppendSwitchIfTrue(builder, "-k", KeepInternalConstructors);
+
+			AppendSwitchIfTrue(builder, "-m", KeepMarshalling);
+
 			return builder.ToString();
 		}
 
@@ -120,5 +128,15 @@ static string GetPortableRootDirectory()
 				Environment.GetFolderPath(Environment.SpecialFolder.ProgramFilesX86, Environment.SpecialFolderOption.DoNotVerify),
 				@"Reference Assemblies\Microsoft\Framework\.NETPortable");
 		}
+
+		static void AppendSwitchIfTrue(CommandLineBuilder builder, string switchName, string value)
+		{
+			if (string.IsNullOrEmpty(value))
+				return;
+
+			bool result;
+			if (bool.TryParse(value, out result))
+				builder.AppendSwitch(switchName);
+		}
 	}
 }

src/Build/NuGet.Build.Packaging.Tasks/NuGet.Build.Packaging.targets

@@ -523,6 +523,8 @@ Copyright (c) .NET Foundation. All rights reserved.
 			IntersectionAssembly="@(IntersectionAssembly)"
 			ReferencePath="$(IntersectionAssemblyReferencePath)"
 			ExcludeType="$(IntersectionExcludeType)"
+			KeepInternalConstructors="$(IntersectionKeepInternalConstructors)"
+			KeepMarshalling="$(IntersectionKeepMarshalling)"
 			ToolPath="$(ApiIntersectToolPath)"
 			ToolExe="$(ApiIntersectToolExe)">
 			<Output TaskParameter="OutputDirectory" ItemName="_ReferenceAssemblyBuildInfo" />