Merged PR 525925: Avoid VisualCppTools.Community.VS2017Layout dependency download on non-windows hosts

Avoid getting VisualCppTools.Community.VS2017Layout on non-windows hosts.

Private/Facades/VisualCppTools.Community.VS2017Layout/VisualCppTools.Community.VS2017Layout.dsc

@@ -0,0 +1,21 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+import {Transformer} from "Sdk.Transformers";
+
+// This is an dummy facade for the VisualCppTools.Community.VS2017Layout package,
+// it's used to avoid downloading the package on non-windows systems
+
+namespace Contents {
+    export declare const qualifier: {
+    };
+
+    @@public
+    export const all: StaticDirectory = Transformer.sealDirectory({
+        root: d`.`,
+        files: []
+    });
+}
+
+@@public
+export const pkg: NugetPackage = {contents: Contents.all, dependencies: []};

Private/Facades/VisualCppTools.Community.VS2017Layout/module.config.dsc

@@ -0,0 +1,7 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+module({
+    name: "VisualCppTools.Community.VS2017Layout",
+    nameResolutionSemantics: NameResolutionSemantics.implicitProjectReferences,
+});

Public/Src/Utilities/Native/BuildXL.Native.dsc

@@ -32,7 +32,9 @@ namespace Native {
 
     @@public
     export const nativeWin = [ 
-        ...addIfLazy(qualifier.targetRuntime === "win-x64", () => [ importFrom("BuildXL.Sandbox.Windows").Deployment.natives ])
+        ...addIfLazy(qualifier.targetRuntime === "win-x64" && Context.getCurrentHost().os === "win", () => [
+            importFrom("BuildXL.Sandbox.Windows").Deployment.natives
+        ])
     ];
 
     @@public

bxl.sh

@@ -14,6 +14,7 @@ declare arg_DeployDevRelease=""
 declare arg_UseDev=""
 declare arg_Minimal=""
 declare arg_Internal=""
+declare arg_Cgmanifest=""
 
 function findMono() {
     local monoLocation=$(which mono)
@@ -66,7 +67,6 @@ function setInternal() {
 function compileWithBxl() {
     local args=(
         --config "$MY_DIR/config.dsc"
-        /generateCgManifestForNugets:"${MY_DIR}/cg/nuget/cgmanifest.json"
         /fancyConsoleMaxStatusPips:10
         /exp:LazySODeletion
         /nowarn:11319 # DX11319: nuget version mismatch
@@ -115,6 +115,10 @@ function parseArgs() {
             arg_Internal="1"
             shift
             ;;
+        --cgmanifest)
+            arg_Cgmanifest="1"
+            shift
+            ;;
         *)
             arg_Positional+=("$1")
             shift
@@ -148,6 +152,10 @@ if [[ -n "$arg_Internal" ]]; then
     setInternal $@
 fi
 
+if [[ -n "$arg_Cgmanifest" ]]; then
+    arg_Positional+=(/generateCgManifestForNugets:"${MY_DIR}/cg/nuget/cgmanifest.json")
+fi
+
 if [[ -n "$arg_UseDev" ]]; then
     if [[ ! -f $MY_DIR/Out/Selfhost/Dev/bxl ]]; then
         print_error "Error: Could not find the dev deployment. Make sure you build with --deploy-dev first."

config.dsc

@@ -30,6 +30,9 @@ config({
                 f`Public/Sdk/Public/Prelude/package.config.dsc`, // Prelude cannot be named module because it is a v1 module
                 f`Public/Sdk/Public/Transformers/package.config.dsc`, // Transformers cannot be renamed yet because office relies on the filename
                 ...globR(d`Public/Sdk`, "module.config.dsc"),
+                ...addIf(Context.getCurrentHost().os !== "win",
+                    f`private/Facades/VisualCppTools.Community.VS2017Layout/module.config.dsc`
+                ),
             ]
         },
         {
@@ -135,7 +138,7 @@ config({
                 { id: "NuGet.Versioning", version: "4.6.0" }, // Can't use the latest becuase nuget extracts to folder with metadata which we don't support yet.
 
                 // Cpp Sdk
-                { id: "VisualCppTools.Community.VS2017Layout", version: "14.11.25506"},
+                ...(Context.getCurrentHost().os === "win" ? [{ id: "VisualCppTools.Community.VS2017Layout", version: "14.11.25506"}] : []),
 
                 // ProjFS (virtual file system)
                 { id: "Microsoft.Windows.ProjFS", version: "1.0.19079.1" },