IRGen: Use -disable-legacy-type-info in original-defined-attr-linker-directives-fail.swift test.

Prevents the following error from occurring when running the test on an arm64 macOS host:

```
error: IR generation failure: Cannot read legacy layout file at '.../swift-project/build/Ninja-RelWithDebInfoAssert/swift-macosx-arm64/lib/swift/macosx/layouts-x86_64.yaml'
```

Author: tshortli

test/IRGen/original-defined-attr-linker-directives-fail.swift

@@ -6,7 +6,7 @@
 // RUN: not %target-swift-frontend -swift-version 4 -enforce-exclusivity=checked %s -emit-ir -module-name CurrentModule -D CURRENT_MODULE -previous-module-installname-map-file %t/nil.json >& %t/error.txt
 // RUN: %FileCheck %s -check-prefix=CHECK-ERROR < %t/error.txt
 
-// RUN: %target-swift-frontend -target x86_64-apple-macosx10.6 -swift-version 4 -enforce-exclusivity=checked %s -emit-ir -module-name CurrentModule -D CURRENT_MODULE -previous-module-installname-map-file %t/install-name.json | %FileCheck %s -check-prefix=CHECK-SYMBOLS-LOW-TARGET
+// RUN: %target-swift-frontend -target x86_64-apple-macosx10.6 -swift-version 4 -enforce-exclusivity=checked %s -emit-ir -disable-legacy-type-info -module-name CurrentModule -D CURRENT_MODULE -previous-module-installname-map-file %t/install-name.json | %FileCheck %s -check-prefix=CHECK-SYMBOLS-LOW-TARGET
 
 @available(OSX 10.8, *)
 @_originallyDefinedIn(module: "OriginalModule", macOS 10.10)