[msbuild] Unify MtouchLink and LinkMode info _LinkMode. (#8764)

msbuild/Xamarin.Mac.Tasks/Xamarin.Mac.Common.props

@@ -74,7 +74,6 @@ Copyright (C) 2013-2014 Xamarin. All rights reserved.
 		<I18n Condition="'$(I18n)' == ''"></I18n>
 		<IncludeMonoRuntime Condition="'$(IncludeMonoRuntime)' == ''">true</IncludeMonoRuntime>
 		<MonoBundlingExtraArgs Condition="'$(MonoBundlingExtraArgs)' == ''"></MonoBundlingExtraArgs>
-		<LinkMode Condition="'$(LinkMode)' == ''">None</LinkMode>
 		<XamMacArch Condition="'$(XamMacArch)' == ''">x86_64</XamMacArch>
 		<IsAppExtension Condition="'$(IsAppExtension)' == ''">False</IsAppExtension>
 		<EnableSGenConc Condition="'$(EnableSGenConc)' == ''">false</EnableSGenConc>

msbuild/Xamarin.Mac.Tasks/Xamarin.Mac.Common.targets

@@ -495,7 +495,7 @@ Copyright (C) 2014 Xamarin. All rights reserved.
 			TargetFrameworkMoniker="$(_ComputedTargetFrameworkMoniker)"
 			Architecture="$(TargetArchitectures)"
 			ArchiveSymbols="$(MonoSymbolArchive)"
-			LinkMode="$(LinkMode)"
+			LinkMode="$(_LinkMode)"
 			Debug="$(MmpDebug)"
 			HttpClientHandler="$(HttpClientHandler)"
 			I18n="$(I18n)"

msbuild/Xamarin.Shared/Xamarin.Shared.props

@@ -55,6 +55,12 @@ Copyright (C) 2020 Microsoft. All rights reserved.
 		<_SdkVersion Condition="'$(_PlatformName)' == 'macOS'">$(MacOSXSdkVersion)</_SdkVersion>
 		<_SdkVersion Condition="'$(_PlatformName)' != 'macOS'">$(MtouchSdkVersion)</_SdkVersion>
 
+		<!-- LinkMode -->
+		<_LinkMode Condition="'$(_LinkMode)' == '' And '$(_PlatformName)' == 'macOS'">$(LinkMode)</_LinkMode>
+		<_LinkMode Condition="'$(_LinkMode)' == '' And '$(_PlatformName)' != 'macOS'">$(MtouchLink)</_LinkMode>
+		<_LinkMode Condition="'$(_LinkMode)' == '' And '$(_PlatformName)' == 'macOS'">None</_LinkMode> <!-- Linking is off by default for macOS apps -->
+		<_LinkMode Condition="'$(_LinkMode)' == '' And '$(_PlatformName)' != 'macOS'">SdkOnly</_LinkMode> <!-- Default linking is SdkOnly for iOS/tvOS/watchOS apps -->
+
 		<!-- RequireCodeSigning -->
 		<!-- iOS/watchOS/tvOS is simple: device builds require code signing, simulator builds do not. This is a big lie, for some simulator builds need to be signed, but the _DetectCodeSigning task handles those cases. -->
 		<_RequireCodeSigning Condition="'$(_PlatformName)' != 'macOS' And '$(_RequireCodeSigning)' == ''">false</_RequireCodeSigning> <!-- Xamarin.iOS builds are not signed by default -->

msbuild/Xamarin.iOS.Tasks.Core/Xamarin.iOS.Common.props

@@ -42,7 +42,6 @@ Copyright (C) 2013-2016 Xamarin. All rights reserved.
 		<MtouchHttpClientHandler Condition="'$(MtouchHttpClientHandler)' == ''">NSUrlSessionHandler</MtouchHttpClientHandler>
 		<MtouchProfiling Condition="'$(MtouchProfiling)' == ''">False</MtouchProfiling>
 		<MtouchLinkerDumpDependencies Condition="'$(MtouchLinkerDumpDependencies)' == ''">False</MtouchLinkerDumpDependencies>
-		<MtouchLink Condition="'$(MtouchLink)' == ''">SdkOnly</MtouchLink>
 		<MtouchUseLlvm Condition="'$(MtouchUseLlvm)' == ''">False</MtouchUseLlvm>
 		<MtouchNoSymbolStrip Condition="'$(MtouchNoSymbolStrip)' == ''">False</MtouchNoSymbolStrip>
 		<MtouchFloat32 Condition="'$(MtouchFloat32)' == ''">False</MtouchFloat32>

msbuild/Xamarin.iOS.Tasks.Core/Xamarin.iOS.Common.targets

@@ -806,7 +806,7 @@ Copyright (C) 2013-2016 Xamarin. All rights reserved.
 			IsAppExtension="$(IsAppExtension)"
 			LinkDescriptions="@(LinkDescription)"
 			LinkerDumpDependencies="$(MtouchLinkerDumpDependencies)"
-			LinkMode="$(MtouchLink)"
+			LinkMode="$(_LinkMode)"
 			MainAssembly="$(TargetPath)"
 			NativeReferences="@(NativeReference)"
 			OutputPath="$(DeviceSpecificOutputPath)"