backends/drm: give the commit threads names

That makes them easier to identify in backtraces

src/backends/drm/drm_commit_thread.cpp

@@ -21,7 +21,7 @@ namespace KWin
 // committing takes about 800µs, the rest is accounting for sleep not being accurate enough
 static constexpr auto s_safetyMargin = 1800us;
 
-DrmCommitThread::DrmCommitThread()
+DrmCommitThread::DrmCommitThread(const QString &name)
 {
     m_thread.reset(QThread::create([this]() {
         gainRealTime();
@@ -80,6 +80,7 @@ DrmCommitThread::DrmCommitThread()
             }
         }
     }));
+    m_thread->setObjectName(name);
     m_thread->start();
 }
 

src/backends/drm/drm_commit_thread.h

@@ -26,7 +26,7 @@ class DrmCommitThread : public QObject
 {
     Q_OBJECT
 public:
-    explicit DrmCommitThread();
+    explicit DrmCommitThread(const QString &name);
     ~DrmCommitThread();
 
     void addCommit(std::unique_ptr<DrmAtomicCommit> &&commit);

src/backends/drm/drm_connector.cpp

@@ -136,8 +136,8 @@ DrmConnector::DrmConnector(DrmGpu *gpu, uint32_t connectorId)
                                                             QByteArrayLiteral("BT2020_RGB"),
                                                             QByteArrayLiteral("BT2020_YCC"),
                                                         })
-    , m_pipeline(std::make_unique<DrmPipeline>(this))
     , m_conn(drmModeGetConnector(gpu->fd(), connectorId))
+    , m_pipeline(m_conn ? std::make_unique<DrmPipeline>(this) : nullptr)
 {
     if (m_conn) {
         for (int i = 0; i < m_conn->count_encoders; ++i) {

src/backends/drm/drm_connector.h

@@ -138,8 +138,8 @@ private:
     QList<std::shared_ptr<DrmConnectorMode>> generateCommonModes();
     std::shared_ptr<DrmConnectorMode> generateMode(const QSize &size, float refreshRate);
 
-    std::unique_ptr<DrmPipeline> m_pipeline;
     DrmUniquePtr<drmModeConnector> m_conn;
+    std::unique_ptr<DrmPipeline> m_pipeline;
     Edid m_edid;
     QSize m_physicalSize = QSize(-1, -1);
     QList<std::shared_ptr<DrmConnectorMode>> m_driverModes;

src/backends/drm/drm_pipeline.cpp

@@ -39,7 +39,7 @@ static const QMap<uint32_t, QVector<uint64_t>> legacyCursorFormats = {{DRM_FORMA
 
 DrmPipeline::DrmPipeline(DrmConnector *conn)
     : m_connector(conn)
-    , m_commitThread(std::make_unique<DrmCommitThread>())
+    , m_commitThread(std::make_unique<DrmCommitThread>(conn->connectorName()))
 {
     QObject::connect(m_commitThread.get(), &DrmCommitThread::commitFailed, [this]() {
         if (m_output) {