Remove group info for SwiftSyntax

AFAICT the group info was only used for swift modules built by `build-script.py`. But since we don’t ship the swift modules as part of the toolchain anymore and the intended way to build SwiftSyntax for clients is through the SwiftPM package, I think the maintainance cost is higher than the value it provides (which I think has always been marginal).

Author: ahoppen

Package.swift

@@ -23,16 +23,9 @@ let swiftSyntaxTarget: PackageDescription.Target
 /// If we are in a controlled CI environment, we can use internal compiler flags
 /// to speed up the build or improve it.
 if ProcessInfo.processInfo.environment["SWIFT_BUILD_SCRIPT_ENVIRONMENT"] != nil {
-  let groupFile = URL(fileURLWithPath: #file)
-    .deletingLastPathComponent()
-    .appendingPathComponent("utils")
-    .appendingPathComponent("group.json")
-
-  var swiftSyntaxUnsafeFlags = ["-Xfrontend", "-group-info-path",
-                                "-Xfrontend", groupFile.path]
   // Enforcing exclusivity increases compile time of release builds by 2 minutes.
   // Disable it when we're in a controlled CI environment.
-  swiftSyntaxUnsafeFlags += ["-enforce-exclusivity=unchecked"]
+  let swiftSyntaxUnsafeFlags = ["-enforce-exclusivity=unchecked"]
 
   swiftSyntaxTarget = .target(name: "SwiftSyntax", dependencies: ["_CSwiftSyntax"],
                               swiftSettings: [.unsafeFlags(swiftSyntaxUnsafeFlags)]

build-script.py

@@ -32,8 +32,6 @@
 
 LIT_EXEC = os.path.join(LLVM_DIR, "utils", "lit", "lit.py")
 
-GROUP_INFO_PATH = os.path.join(PACKAGE_DIR, "utils", "group.json")
-
 BASE_KIND_FILES = {
     "Decl": "SyntaxDeclNodes.swift",
     "Expr": "SyntaxExprNodes.swift",