[clang] [Clang][DirectX] Always use Diagnostic Printer (PR #135655)

[Eli Friedman via cfe-commits]

================
@@ -2,7 +2,6 @@
 // RUN: not %clang_cc1 %s -o - -S -triple=amdgcn-amd-amdhsa 2>&1 | FileCheck %s
 
 void test_amdgcn_fence_failure() {
-
-  // CHECK: error: Unsupported atomic synchronization scope
+  // CHECK: error: <unknown>:0:0: in function _Z25test_amdgcn_fence_failurev void (): Unsupported atomic synchronization scope
----------------
efriedma-quic wrote:

Current diagnostic without debug info:

```
<stdin>:1:6: error: Unsupported atomic synchronization scope
    1 | void test_amdgcn_fence_failure() {
      |      ^
```

Current diagnostic with debug info:

```
<stdin>:3:3: error: Unsupported atomic synchronization scope
    3 |   __builtin_amdgcn_fence(__ATOMIC_SEQ_CST, "foobar");
      |   ^
```

The one without debug info could maybe be improved a bit, but throwing away the location info doesn't seem like the right approach.

https://github.com/llvm/llvm-project/pull/135655