QThread/Win: set the thread name on non-MSVC also

SetThreadDescription is a Win32 API provided by Kernel32.dll, the only
thing that MinGW is missing is the declaration of the function. We can
provide it ourselves.

Change-Id: Iad5fc6cb7b6eb190310f5888326b65f50ddbdca8
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/thread/qthread_win.cpp

@@ -18,7 +18,17 @@
 #  define _MT
 #endif // _MT
 #include <process.h>
-#include <processthreadsapi.h>
+
+extern "C" {
+// MinGW is missing the declaration of SetThreadDescription:
+WINBASEAPI
+HRESULT
+WINAPI
+SetThreadDescription(
+    _In_ HANDLE hThread,
+    _In_ PCWSTR lpThreadDescription
+    );
+}
 
 QT_BEGIN_NAMESPACE
 
@@ -246,13 +256,11 @@ unsigned int __stdcall QT_ENSURE_STACK_ALIGNED_FOR_SSE QThreadPrivate::start(voi
     data->ensureEventDispatcher();
     data->eventDispatcher.loadRelaxed()->startingUp();
 
-#if defined(Q_CC_MSVC)
     // sets the name of the current thread.
     QString threadName = std::exchange(thr->d_func()->objectName, {});
     if (Q_LIKELY(threadName.isEmpty()))
         threadName = QString::fromUtf8(thr->metaObject()->className());
     SetThreadDescription(GetCurrentThread(), reinterpret_cast<const wchar_t *>(threadName.utf16()));
-#endif
 
     emit thr->started(QThread::QPrivateSignal());
     QThread::setTerminationEnabled(true);