Windows doesn't support `pthread_attr`, which was introduced to asan_test.cpp in #165198, so this change `#ifdef`s out the changes made in that PR. Originally reported by Chrome as https://crbug.com/459880605.
Windows doesn't support `pthread_attr`, which was introduced to asan_test.cpp in #165198, so this change `#ifdef`s out the changes made in that PR. Originally reported by Chrome as https://crbug.com/459880605.