CMake: Only start parsing when creator gets focus again

Rip out QFileSystemWatcher and use Qt Creators IDocument for file
watching instead. The latter properly delays any action till creator
gets focus again.

Task-number: QTCREATORBUG-16354
Change-Id: Ibb71963416b09712a80ee95347425550453b7fd4
Reviewed-by: Tim Jenssen <tim.jenssen@theqtcompany.com>

src/plugins/cmakeprojectmanager/cmakebuildconfiguration.h

@@ -52,6 +52,8 @@ public:
     CMakeBuildConfiguration(ProjectExplorer::Target *parent);
     ~CMakeBuildConfiguration();
 
+    void cmakeFilesChanged();
+
     bool isEnabled() const override;
     QString disabledReason() const override;