[Xamarin.Android.Build.Tasks] Strip AOT .sos when linking (#6842)

Fixes: #6840

Context: b21cbf9

Commit b21cbf9 contained a TODO:

> TODO: the Resulting `.apk` sizes also increase[d] unexpectedly, with
> `Xamarin.Forms_Performance_Integration-Signed-Release-Profiled-Aot.apkdesc`
> showing a 1.7MB increase in `.apk` size.  We believe that this is
> because of more verbose debug symbols.
> #6840 will track this.

Update the `<GetAotArguments/>` MSBuild task to add the `-s` linker
flag to `GetAotArguments.LdFlags`.  This will cause the native linker
to produce shared AOT libraries without debug symbols.

Debug symbols are stripped unless the `$(DebugSymbols)`=True.

This fixes the size regression in
`Xamarin.Forms_Performance_Integration-Signed-Release-Profiled-Aot.apkdesc`,
shrinking PackageSize from 19,475,110 down to 16,061,636.
Compare to the pre-b21cbf94 PackageSize of 17,713,830: we're now
1.6MB *smaller* than b21cbf9!

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.Aot.targets

@@ -58,7 +58,8 @@ They run in a context of an inner build with a single $(RuntimeIdentifier).
         AotOutputDirectory="$(_AndroidAotBinDirectory)"
         RuntimeIdentifier="$(RuntimeIdentifier)"
         EnableLLVM="$(EnableLLVM)"
-        Profiles="@(AndroidAotProfile)">
+        Profiles="@(AndroidAotProfile)"
+        StripLibraries="$(_AndroidAotStripLibraries)">
       <Output PropertyName="_Triple"     TaskParameter="Triple" />
       <Output PropertyName="_ToolPrefix" TaskParameter="ToolPrefix" />
       <Output PropertyName="_MsymPath"   TaskParameter="MsymPath" />

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.AssemblyResolution.targets

@@ -204,26 +204,6 @@ _ResolveAssemblies MSBuild target.
         IncludeDebugSymbols="$(AndroidIncludeDebugSymbols)">
       <Output TaskParameter="OutputLibraries" ItemName="FrameworkNativeLibrary" />
     </ProcessNativeLibraries>
-    <ItemGroup>
-      <_StrippedFrameworkNativeLibrary Include="@(FrameworkNativeLibrary->'$(IntermediateOutputPath)native\%(RuntimeIdentifier)\%(Filename)%(Extension)')" />
-    </ItemGroup>
-  </Target>
-
-  <Target Name="_StripFrameworkNativeLibraries"
-      Condition=" '$(AndroidIncludeDebugSymbols)' != 'true' "
-      DependsOnTargets="_IncludeNativeSystemLibraries"
-      Inputs="@(FrameworkNativeLibrary)"
-      Outputs="@(_StrippedFrameworkNativeLibrary)">
-    <StripNativeLibraries
-        SourceFiles="@(FrameworkNativeLibrary)"
-        DestinationFiles="@(_StrippedFrameworkNativeLibrary)"
-        ToolPath="$(AndroidBinUtilsDirectory)"
-    />
-    <ItemGroup Condition=" '$(AndroidIncludeDebugSymbols)' != 'true' ">
-      <FrameworkNativeLibrary Remove="@(FrameworkNativeLibrary)"/>
-      <FrameworkNativeLibrary Include="@(_StrippedFrameworkNativeLibrary)"/>
-      <FileWrites Include="@(_StrippedFrameworkNativeLibrary)" />
-    </ItemGroup>
   </Target>
 
 </Project>

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.BuildOrder.targets

@@ -74,7 +74,6 @@ projects, these properties are set in Xamarin.Android.Legacy.targets.
       _CheckApkPerAbiFlag;
       _LintChecks;
       _IncludeNativeSystemLibraries;
-      _StripFrameworkNativeLibraries;
       _CheckGoogleSdkRequirements;
     </_PrepareBuildApkDependsOnTargets>
   </PropertyGroup>

src/Xamarin.Android.Build.Tasks/Tasks/GetAotArguments.cs

@@ -47,6 +47,8 @@ public abstract class GetAotArguments : AndroidAsyncTask
 
 		public bool EnableLLVM { get; set; }
 
+		public bool StripLibraries { get; set; }
+
 		public string AndroidSequencePointsMode { get; set; } = "";
 
 		public ITaskItem [] Profiles { get; set; } = Array.Empty<ITaskItem> ();
@@ -291,7 +293,17 @@ string GetLdFlags(NdkTools ndk, AndroidTargetArch arch, int level, string toolPr
 
 				ldFlags = $"\\\"{string.Join ("\\\";\\\"", libs)}\\\"";
 			}
-			return ldFlags;
+
+			if (!StripLibraries) {
+				return ldFlags;
+			}
+
+			const string StripFlag = "-s";
+			if (ldFlags.Length == 0) {
+				return StripFlag;
+			}
+
+			return $"{ldFlags} {StripFlag}";
 		}
 
 		static string GetNdkToolchainLibraryDir (NdkTools ndk, string binDir, string archDir = null)

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/XASdkTests.cs

@@ -598,13 +598,6 @@ public void DotNetBuild (string runtimeIdentifiers, bool isRelease, bool aot, bo
 			}
 
 			var rids = runtimeIdentifiers.Split (';');
-			if (isRelease) {
-				// Check for stripped native libraries
-				foreach (var rid in rids) {
-					FileAssert.Exists (Path.Combine (intermediateOutputPath, "native", rid, "libmono-android.release.so"));
-					FileAssert.Exists (Path.Combine (intermediateOutputPath, "native", rid, "libmonosgen-2.0.so"));
-				}
-			}
 
 			// Check AndroidManifest.xml
 			var manifestPath = Path.Combine (intermediateOutputPath, "android", "AndroidManifest.xml");

src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets

@@ -329,6 +329,7 @@ Copyright (C) 2011-2012 Xamarin. All rights reserved.
 </Choose>
 
 <PropertyGroup>
+  <_AndroidAotStripLibraries Condition=" '$(_AndroidAotStripLibraries)' == '' And '$(AndroidIncludeDebugSymbols)' != 'true' ">True</_AndroidAotStripLibraries>
   <AndroidUseAssemblyStore Condition=" '$(AndroidUseAssemblyStore)' == '' and ('$(EmbedAssembliesIntoApk)' != 'true' or '$(AndroidIncludeDebugSymbols)' == 'true' or '$(BundleAssemblies)' == 'true') ">false</AndroidUseAssemblyStore>
   <AndroidUseAssemblyStore Condition=" '$(AndroidUseAssemblyStore)' == '' ">true</AndroidUseAssemblyStore>
 </PropertyGroup>

src/Xamarin.Android.Build.Tasks/Xamarin.Android.Legacy.targets

@@ -708,7 +708,8 @@ projects. .NET 5 projects will not import this file.
         AdditionalNativeLibraryReferences="@(_AdditionalNativeLibraryReferences)"
         YieldDuringToolExecution="$(YieldDuringToolExecution)"
         EnableLLVM="$(EnableLLVM)"
-        Profiles="@(_AotProfiles)">
+        Profiles="@(_AotProfiles)"
+        StripLibraries="$(_AndroidAotStripLibraries)">
       <Output TaskParameter="NativeLibrariesReferences" ItemName="_AdditionalNativeLibraryReferences" />
     </Aot>