CMake: Fix build directory for "Add Buildconfiguration"

Task-number: QTCREATORBUG-8425

Change-Id: I58a47895fa882bcc53cad1ef764a307c714f2a1b
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/plugins/cmakeprojectmanager/cmakeproject.h

@@ -94,8 +94,8 @@ public:
 
     CMakeBuildTarget buildTargetForTitle(const QString &title);
 
-    QString defaultBuildDirectory() const;
-
+    QString shadowBuildDirectory(const QString &projectFilePath, const ProjectExplorer::Kit *k,
+                                 const QString &bcName);
 
     QString uicCommand() const;