Docker: Fix searching for clangd

Environment::searchInPath() does not know from which device it came.
Therefore it will take the PATH variable as it is ( without the
device://... prefix ) and search for files on the local device.

Change-Id: Iecddb5ee1beb4ac821a9ac592f6edb1fc0f68b54
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/docker/dockerdevicewidget.cpp

@@ -182,10 +182,13 @@ DockerDeviceWidget::DockerDeviceWidget(const IDevice::Ptr &device)
         logView->clear();
         dockerDevice->updateContainerAccess();
 
-        const FilePath clangdPath = dockerDevice->systemEnvironment()
+        const FilePath clangdPath = dockerDevice->filePath("clangd")
-                                        .searchInPath("clangd", {}, [](const FilePath &clangd) {
+                                        .searchInPath({},
+                                                      FilePath::AppendToPath,
+                                                      [](const FilePath &clangd) {
                                                           return Utils::checkClangdVersion(clangd);
                                                       });
+
         if (!clangdPath.isEmpty())
             m_clangdExecutable->setFilePath(clangdPath);