[xaprepare] Check in Ndk.projitems, remove generator

[jonathanpeppers]

Mirrors #11608 (which checked in Mono.Android.Apis.projitems the same way). See also #11568, #11580, #11613, #11631, #11657, #11658.

What

build-tools/scripts/Ndk.projitems.in was a template with @NDK_*@ placeholders that the Get_Ndk_projitems generator in xaprepare filled in from constants in BuildAndroidPlatforms.cs. Those substitution values only change on rare NDK bumps, so generating the file on every build adds no value.

This PR checks in the resolved file as a static build-tools/scripts/Ndk.projitems and removes the generator.

Changes

• Add build-tools/scripts/Ndk.projitems — the static, checked-in file. Rather than hardcoding values, it sources them from the existing properties in Configuration.props (which is imported before Ndk.targets):

  • AndroidNdkVersion → $(_XAAndroidNdkRelease)
  • AndroidNdkPkgRevision → $(_XAAndroidNdkPkgRevision)
  • the per-ABI AndroidNdkApiLevel_* → $(AndroidMinimumDotNetApiLevel)

  So there is nothing to keep in sync on an NDK/API bump.

• build-tools/scripts/Ndk.targets — point ProjitemsFile at the new in-tree location ($(MSBuildThisFileDirectory)Ndk.projitems) instead of bin/Build$(Configuration)/Ndk.projitems.

• Delete build-tools/scripts/Ndk.projitems.in.

• Step_GenerateFiles.cs — remove the Get_Ndk_projitems method and its dispatch entry.

• Configurables.cs — update a doc comment reference from Ndk.projitems.in → Ndk.projitems.

Simplifications (from review)

• Collapsed the dead legacy/NET API-level split. The legacy 32-bit minimum API level used to be lower than the .NET minimum, but they are identical now. Removed the two per-ABI properties that nothing references (AndroidNdkApiLevel_Arm, AndroidNdkApiLevel_X86_Legacy). The arm64-v8a/x86_64 properties are kept because shipped targets (Build.Tasks.targets, Common.props.in, NativeAOT.targets) still consume them by name.
• Removed the ApiLevelNET item metadata. ApiLevelNET was the .NET (.NET 6+) Android minimum API level vs. the legacy Xamarin.Android/Mono ApiLevel; the two are identical now and this repo is .NET-only. Its only consumer was src/native/common/libunwind/libunwind-xamarin.targets, which now reads ApiLevel. Dropped ApiLevelNET from all four AndroidSupportedTargetJitAbi items.

The NDK constants in BuildAndroidPlatforms.cs are intentionally left untouched — they're still consumed by Get_XABuildConfig_cs and the cmake presets generator.

Verification

• dotnet build build-tools/xaprepare/xaprepare/xaprepare.csproj -c Debug → 0 errors / 0 warnings.
• Evaluated the import chain via a standalone MSBuild harness (importing the real Configuration.props); it produces all four AndroidSupportedTargetJitAbi items with ApiLevel=24 and the expected AndroidRID metadata, matching prior generator output (NDK 28c / pkg 28.2.13676358).
• Audits clean: git grep Ndk.projitems.in, git grep Ndk_projitems, git grep ApiLevelNET, and the old bin/Build$(Configuration)/Ndk.projitems path all return 0 hits.

[Copilot]

Pull request overview

This PR continues the xaprepare cleanup by checking in build-tools/scripts/Ndk.projitems as a static file and removing the Get_Ndk_projitems generator path from Step_GenerateFiles, so builds no longer regenerate a file whose contents only change on NDK bumps.

Changes:

• Check in a resolved build-tools/scripts/Ndk.projitems (NDK 28c / pkg rev 28.2.13676358 / min API 24) and stop generating it at prepare time.
• Update build-tools/scripts/Ndk.targets to import the in-tree projitems instead of bin/Build$(Configuration)/....
• Remove the Get_Ndk_projitems generator method/dispatch and update related documentation references.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
build-tools/xaprepare/xaprepare/Steps/Step_GenerateFiles.cs	Removes the Ndk.projitems generation step from the xaprepare file-generation list.
build-tools/xaprepare/xaprepare/ConfigAndData/Configurables.cs	Updates doc comment to point at the checked-in projitems file.
build-tools/scripts/Ndk.targets	Imports Ndk.projitems from the scripts directory instead of from bin/Build$(Configuration).
build-tools/scripts/Ndk.projitems	Adds the resolved, checked-in projitems file that defines NDK version/pkg revision and ABI metadata.

Comments suppressed due to low confidence (2)

build-tools/scripts/Ndk.targets:8

• Ndk.projitems is now checked in, so the Exists(...) condition on the <Import> can hide a missing/incorrect checkout and lead to confusing downstream MSBuild errors (the items/properties would just not be defined). Consider removing the condition so the build fails fast if the file is missing.

    <ProjitemsFile>$(MSBuildThisFileDirectory)Ndk.projitems</ProjitemsFile>
  </PropertyGroup>
  <Import
      Project="$(ProjitemsFile)"
      Condition="Exists('$(ProjitemsFile)')"/>

build-tools/scripts/Ndk.projitems:6

• The header comment says to update API-level values when changing NdkMinimumAPI/NdkMinimumAPILegacy32 in BuildAndroidPlatforms.cs, but those values are actually sourced from $(AndroidMinimumDotNetApiLevel) (Configuration.props). To avoid future mismatches, the comment should point at Configuration.props for API-level changes (and at BuildAndroidPlatforms.cs for NDK version/revision).