ksuinit: add build tool

[5ec1cff]

No description provided.

[Copilot]

Pull request overview

Adds a dedicated Rust-based build helper for ksuinit and wires it into the userspace Cargo configuration so CI (and developers) can build ksuinit via a cargo alias.

Changes:

• Introduce userspace/tools crate with a build-ksuinit binary that sets up the linker/RUSTFLAGS and runs cargo build for userspace/ksuinit.
• Add userspace/.cargo/config.toml alias (cargo build-ksuinit) to invoke the new tool.
• Update the ksuinit GitHub Actions workflow to use the alias, and adjust ksuinit’s .gitignore to track an example Cargo config.

Reviewed changes

Copilot reviewed 6 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
userspace/tools/src/bin/build-ksuinit.rs	New build helper that locates the NDK linker and runs the ksuinit release build.
userspace/tools/Cargo.toml	Defines the new tools crate and build-ksuinit binary target.
userspace/tools/Cargo.lock	Lockfile for the new tools crate.
userspace/tools/.gitignore	Ignores build artifacts for the new crate.
userspace/ksuinit/.gitignore	Stops ignoring the whole .cargo/ dir; ignores only .cargo/config.toml.
userspace/ksuinit/.cargo/config.example.toml	Adds a tracked example Cargo config for developers/rust-analyzer.
userspace/.cargo/config.toml	Adds cargo build-ksuinit alias to run the new tool.
.github/workflows/ksuinit.yml	Switches CI build step to cargo build-ksuinit.

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[Copilot]

The build tool errors out if ANDROID_NDK_HOME is unset, but this workflow doesn't install/configure the Android NDK or export ANDROID_NDK_HOME. As a result, the CI job will fail on runners where ANDROID_NDK_HOME is not preconfigured. Consider adding an Android SDK/NDK setup step (pin an NDK version) and explicitly setting ANDROID_NDK_HOME before calling cargo build-ksuinit, or update the tool to derive the NDK path from ANDROID_SDK_ROOT/ANDROID_HOME when ANDROID_NDK_HOME is missing.

Suggested change

	- name: Build ksuinit
	- name: Set up Android SDK and NDK
	uses: android-actions/setup-android@v3
	with:
	ndk-version: 25.2.9519653
	- name: Build ksuinit
	env:
	ANDROID_NDK_HOME: ${{ env.ANDROID_NDK_ROOT }}

[Copilot]

For consistency with the other Rust userspace crates (e.g., userspace/ksuinit/.gitignore and userspace/ksud/.gitignore), consider using /target here instead of target so the rule only applies to the crate root and doesn't accidentally ignore any nested target directories.

Suggested change

	target
	/target