CppTools: Call ProjectInfo::finish when we get it

No need to require the project managers to do this. Also, it is easy to
forget.

Change-Id: I96f7a5e5547418678af9653e5753c372f0880e5a
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/qbsprojectmanager/qbsproject.cpp

@@ -1030,8 +1030,6 @@ void QbsProject::updateCppCodeModel()
         }
     }
 
-    pinfo.finish();
-
     CppTools::GeneratedCodeModelSupport::update(m_extraCompilers);
 
     // Update the code model