Add Swift SDK info in PD context

I see we have added Git information on PD context recently.

Can we add Swift SDK path info here too?

I found I need some include information related to it on non-Darwin platform when writing C target code in SwiftPM.

Currently, I have to use some environment trick here to manually inject it and read it in the package manifest file.

// Package.swift
let SDKPath = ProcessInfo.processInfo.environment["xx"] ?? "" // or Context.environment["xx"]
let includePath = SDKPath.appending("../usr/lib/swift_static")

let targetA: Target = .target(
    name: "A",
    cSettings: [
        .unsafeFlags(["-I", includePath]),

There is also a trick to rely on "_" environment value which will be swift executable path.

let swiftBinPath = Context.environment["_"] ?? ""
let swiftBinURL = URL(fileURLWithPath: swiftBinPath)
let SDKPath = swiftBinURL.deletingLastPathComponent().deletingLastPathComponent().path
let includePath = SDKPath.appending("/lib/swift_static")

Anyway, none of those methods are simple nor reliable. And that's why I'm expecting PackageDescription module can provide such info via Context.