[CIR][Test] Add crash tests for common STL features hitting NYI code

Add XFAIL tests documenting known crashes when using common C++ standard
library features. These tests serve as:
1. Documentation of known limitations
2. Regression tests to detect when features become available
3. Minimal reproducers for future implementation work

New crash tests:
- exception-ptr.cpp: std::make_exception_ptr crashes (exception handling NYI)
- async-future.cpp: std::async/std::future crashes (exception handling NYI)
- filesystem-sd-automatic.cpp: std::filesystem range-for crashes (SD_Automatic NYI)
- tls-destructor.cpp: thread_local with non-trivial destructor (TLS destructors NYI)

All tests are minimal reproducers derived from real-world usage patterns
that currently hit unimplemented code paths in ClangIR.

These issues are tracked in the cleanup/exception/destructor system design
category, requiring architectural decisions before implementation.

Test Plan:
- All 4 new tests marked XFAIL and fail as expected
- Total crash tests: 15 XFAIL tests in clang/test/CIR/crashes/
- No regressions in existing tests

Author: lanza

clang/test/CIR/crashes/async-future.cpp

@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir -fcxx-exceptions -fexceptions
+// XFAIL: *
+//
+// std::async/std::future crashes - exception handling NYI
+// Related to exception system design
+
+#include <future>
+
+void test() {
+  auto f = std::async(std::launch::async, []{ return 42; });
+  int result = f.get();
+}

clang/test/CIR/crashes/exception-ptr.cpp

@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir -fcxx-exceptions -fexceptions
+// XFAIL: *
+//
+// std::make_exception_ptr crashes - exception handling NYI
+// Related to exception system design
+
+#include <exception>
+#include <stdexcept>
+
+void test() {
+  std::exception_ptr ep = std::make_exception_ptr(std::runtime_error("test"));
+}

clang/test/CIR/crashes/filesystem-sd-automatic.cpp

@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir -std=c++17
+// XFAIL: *
+//
+// std::filesystem with range-for crashes - SD_Automatic not implemented
+// Location: CIRGenExpr.cpp:2356
+
+#include <filesystem>
+
+void test() {
+  namespace fs = std::filesystem;
+
+  // This triggers SD_Automatic for the directory_iterator temporary
+  for (const auto& entry : fs::directory_iterator("/tmp")) {
+    auto path = entry.path();
+  }
+}

clang/test/CIR/crashes/tls-destructor.cpp

@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
+// XFAIL: *
+//
+// thread_local with non-trivial destructor not implemented
+// Location: CIRGenCXX.cpp:264
+// Note: Simple TLS works; only destructors are NYI
+
+#include <string>
+
+thread_local std::string tls_string = "hello";
+
+int test() {
+  return tls_string.length();
+}