tests: remove the now unused option -new-mangling-for-tests

Author: eeckstein

lib/Basic/Mangler.cpp

@@ -21,10 +21,6 @@
 using namespace swift;
 using namespace Mangle;
 
-llvm::cl::opt<bool> MangleForTests(
-                       "new-mangling-for-tests", llvm::cl::init(false),
-                       llvm::cl::desc("Use new mangling for compiler tests"));
-
 #ifndef NDEBUG
 
 llvm::cl::opt<bool> PrintSwiftManglingStats(

test/ClangImporter/attr-swift_private.swift

@@ -2,7 +2,7 @@
 // RUN: %build-clang-importer-objc-overlays
 
 // RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk-nosource -I %t) -I %S/Inputs/custom-modules -typecheck %s -verify -verify-ignore-unknown
-// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk-nosource -I %t) -Xllvm -new-mangling-for-tests -I %S/Inputs/custom-modules -emit-ir %s -D IRGEN | %FileCheck %s
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk-nosource -I %t) -I %S/Inputs/custom-modules -emit-ir %s -D IRGEN | %FileCheck %s
 
 // RUN: %target-swift-ide-test(mock-sdk: %clang-importer-sdk-nosource -I %t) -I %S/Inputs/custom-modules -print-module -source-filename="%s" -module-to-print SwiftPrivateAttr > %t.txt
 // RUN: %FileCheck -check-prefix=GENERATED-NEGATIVE %s < %t.txt