Fix libFuzzer not building with pthreads on Windows (#109525)

Fixes https://github.com/llvm/llvm-project/issues/106871

GitOrigin-RevId: b4130bee6bfd34d8045f02fc9f951bcb5db9d85c

FuzzerUtilWindows.cpp

diff --git a/FuzzerUtilWindows.cpp b/FuzzerUtilWindows.cpp
index e0210aa..37aecae 100644
--- a/FuzzerUtilWindows.cpp
+++ b/FuzzerUtilWindows.cpp
@@ -239,6 +239,10 @@
 }
 
 void SetThreadName(std::thread &thread, const std::string &name) {
+#if defined(_LIBCPP_HAS_THREAD_API_PTHREAD) ||                                 \
+    defined(_GLIBCXX_GCC_GTHR_POSIX_H)
+  (void)pthread_setname_np(thread.native_handle(), name.c_str());
+#else
   typedef HRESULT(WINAPI * proc)(HANDLE, PCWSTR);
   HMODULE kbase = GetModuleHandleA("KernelBase.dll");
   proc ThreadNameProc = reinterpret_cast<proc>(
@@ -253,6 +257,7 @@
       }
     }
   }
+#endif
 }
 
 } // namespace fuzzer