Rename the libswift directory to SwiftCompilerSources

SwiftCompilerSources/Package.swift

@@ -0,0 +1,43 @@
+// swift-tools-version:5.3
+
+import PackageDescription
+
+let package = Package(
+  name: "libswift",
+  platforms: [
+    .macOS("10.9"),
+  ],
+  products: [
+    .library(
+      name: "Swift",
+      type: .static,
+      targets: ["SIL", "Optimizer", "ExperimentalRegex"]),
+  ],
+  dependencies: [
+  ],
+  // Note that all modules must be added to LIBSWIFT_MODULES in the top-level
+  // CMakeLists.txt file to get debugging working.
+  targets: [
+    .target(
+      name: "SIL",
+      dependencies: [],
+      swiftSettings: [SwiftSetting.unsafeFlags([
+          "-I", "../include/swift",
+          "-cross-module-optimization"
+        ])]),
+    .target(
+      name: "ExperimentalRegex",
+      dependencies: [],
+      swiftSettings: [SwiftSetting.unsafeFlags([
+          "-I", "../include/swift",
+          "-cross-module-optimization"
+        ])]),
+    .target(
+      name: "Optimizer",
+      dependencies: ["SIL", "ExperimentalRegex"],
+      swiftSettings: [SwiftSetting.unsafeFlags([
+          "-I", "../include/swift",
+          "-cross-module-optimization"
+        ])]),
+  ]
+)