CMake: Do not continue watching files after a different BC got active

Change-Id: Ib044a168c2f4e8153cd89dac2a98a80cddb14513
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/cmakeprojectmanager/builddirmanager.cpp

@@ -191,6 +191,9 @@ void BuildDirManager::resetData()
 {
     m_hasData = false;
 
+    qDeleteAll(m_watchedFiles);
+    m_watchedFiles.clear();
+
     m_cmakeCache.clear();
     m_projectName.clear();
     m_buildTargets.clear();