[dotnet] Fix the identity for mono's dynamic libraries.

dotnet/targets/Xamarin.Shared.Sdk.targets

@@ -220,8 +220,32 @@
 		</CompileNativeCode>
 	</Target>
 
+
+	<!-- The .dylibs shipped with mono comes with the original identity:
+
+	$ otool -l ~/.nuget/packages/microsoft.netcore.app.runtime.ios-x64/5.0.0-*/runtimes/ios-x64/native/libSystem.IO.Compression.Native.dylib | grep LC_ID_DYLIB -A 2
+          cmd LC_ID_DYLIB
+      cmdsize 184
+         name /Users/runner/runners/2.165.2/work/1/s/artifacts/obj/native/netcoreapp5.0-iOS-Release-x64/System.IO.Compression.Native/libSystem.IO.Compression.Native.dylib (offset 24)
+
+	This doesn't work after linking with these libraries, so this must be fixed to be @executable_path/. Eventually mono will ship dylibs we don't have to fix (https://github.com/dotnet/runtime/issues/34637).
+	-->
+	<Target Name="_UpdateDynamicLibraryId" DependsOnTargets="_ComputeVariables" Inputs="@(_MonoLibrary)" Outputs="@(_MonoLibrary -> '$(_IntermediateNativeLibraryDir)%(Filename)%(Extension)')">
+		<!-- install_name_tool modifies the file in-place, so copy it first to a temporary directory before we fix it -->
+		<Copy SourceFiles="%(_MonoLibrary.FullPath)" DestinationFolder="$(_IntermediateNativeLibraryDir)" />
+		<Exec Command="install_name_tool -id @executable_path/%(_MonoLibrary.Filename)%(_MonoLibrary.Extension) $(_IntermediateNativeLibraryDir)%(_MonoLibrary.Filename)%(_MonoLibrary.Extension)" />
+		<!-- Update our item groups -->
+		<ItemGroup>
+			<_MonoLibraryFixed Include="@(_MonoLibrary -> '$(_IntermediateNativeLibraryDir)%(Filename)%(Extension)')" />
+			<ResolvedFileToPublish Remove="@(_MonoLibrary)" />
+			<ResolvedFileToPublish Include="@(_MonoLibraryFixed)" />
+			<_MonoLibrary Remove="@(_MonoLibrary)" />
+			<_MonoLibrary Include="@(_MonoLibraryFixed)" />
+		</ItemGroup>
+	</Target>
+
 	<Target Name="_LinkNativeExecutable"
-			DependsOnTargets="_DetectSdkLocations;_ComputeTargetArchitectures;_GenerateBundleName;_CompileNativeExecutable;_CompileAppManifest"
+			DependsOnTargets="_DetectSdkLocations;_ComputeTargetArchitectures;_GenerateBundleName;_CompileNativeExecutable;_CompileAppManifest;_UpdateDynamicLibraryId"
 			Inputs="@(_NativeExecutableObjectFiles)"
 			Outputs="$(_IntermediateNativeLibraryDir)$(_NativeExecutableName)"
 		>