third_party/libcxxabi: Add test suite (#1076)

Added the `libcxxabi` test suite as found in LLVM 17.0.6.

Some tests that do not apply to the current configuration of
comsopolitan are not added. These include:
- `backtrace_test`, `forced_unwind*`: Use unwind function unsupported in
SjLj mode.
- `noexception*`: Designed to test `libcxxabi` in no exceptions mode.

Some tests are added but not enabled due to bugs specific to GCC or
cosmopolitan. These are clearly indicated in the `BUILD.mk` file.

third_party/libcxxabi/test/test_vector3.pass.cc

@@ -0,0 +1,66 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: no-exceptions
+
+#include "third_party/libcxxabi/include/cxxabi.h"
+
+#include "libc/isystem/stdio.h"
+#include "libc/isystem/stdlib.h"
+#include "libc/isystem/assert.h"
+#include "third_party/libcxx/exception"
+
+#include "third_party/libcxx/memory"
+
+// Disable warning about throw always calling terminate.
+#if defined(__GNUC__) && !defined(__clang__)
+# pragma GCC diagnostic ignored "-Wterminate"
+#endif
+
+// use dtors instead of try/catch
+namespace test1 {
+    struct B {
+         ~B() {
+            printf("should not be run\n");
+            exit(10);
+            }
+};
+
+struct A {
+ ~A()
+#if __has_feature(cxx_noexcept)
+    noexcept(false)
+#endif
+ {
+   B b;
+   throw 0;
+ }
+};
+}  // test1
+
+void my_terminate() { exit(0); }
+
+template <class T>
+void destroy(void* v)
+{
+  T* t = static_cast<T*>(v);
+  t->~T();
+}
+
+int main(int, char**)
+{
+  std::set_terminate(my_terminate);
+  {
+  typedef test1::A Array[10];
+  Array a[10]; // calls _cxa_vec_dtor
+  __cxxabiv1::__cxa_vec_dtor(a, 10, sizeof(test1::A), destroy<test1::A>);
+  assert(false);
+  }
+
+  return 0;
+}