[msbuild] Don't strip dylibs from the .NET runtime

The .NET runtime dylibs (from Microsoft.NETCore.App.Runtime.* NuGet
packages) may contain symbols referenced by indirect symbol table
entries that can't be stripped. Set NoSymbolStrip=true for these items
in _CollectItemsForPostProcessing.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: rolfbjarne

msbuild/Xamarin.Shared/Xamarin.Shared.targets

@@ -2962,6 +2962,11 @@ Copyright (C) 2018 Microsoft. All rights reserved.
 				<BCSymbolMapName>%(Filename)%(Extension).bcsymbolmap</BCSymbolMapName>
 			</_PostProcessingItem>
 
+			<!-- Don't strip dylibs from the .NET runtime - they may contain symbols that can't be stripped -->
+			<_PostProcessingItem Condition="$([MSBuild]::ValueOrDefault('%(_PostProcessingItem.NuGetPackageId)', '').StartsWith('Microsoft.NETCore.App.Runtime'))">
+				<NoSymbolStrip>true</NoSymbolStrip>
+			</_PostProcessingItem>
+
 			<!-- Add any items from app extensions -->
 			<_PostProcessingAppExtensions Include="@(_AppExtensionPostProcessingItems)" Condition="'%(_AppExtensionPostProcessingItems.IsAppExtension)' == 'true' And '%(_AppExtensionPostProcessingItems.IsXPCService)' != 'true'" />
 			<_PostProcessingXpcServices Include="@(_AppExtensionPostProcessingItems)" Condition="'%(_AppExtensionPostProcessingItems.IsAppExtension)' == 'true' And '%(_AppExtensionPostProcessingItems.IsXPCService)' == 'true'" />