CppTools: De-duplicate and rename function in ProjectPart

Change-Id: I675ce4c9059d8ae4046f6a13aa7c04b88141d443
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/cpptools/projectpart.h

@@ -93,6 +93,7 @@ public:
 
 public:
     QString id() const;
+    QString projectFileLocation() const;
 
     Ptr copy() const;
     void updateLanguageFeatures();