Cmake: Replace connect/disconnect of builddirmanager

... by a permanent connection, and only evaluate output for the
active build configuration.

Task-number: QTCREATORBUG-21235
Change-Id: I06f87f7ea680f8f25687a0c5ffc936c801ab7de0
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/cmakeprojectmanager/cmakebuildconfiguration.cpp

@@ -170,6 +170,14 @@ CMakeBuildConfiguration::CMakeBuildConfiguration(Target *parent, Core::Id id)
                                               BuildDirManager::REPARSE_FORCE_CONFIGURATION);
         }
     });
+
+    connect(parent->project(), &Project::projectFileIsDirty, this, [this]() {
+        if (isActive()) {
+            m_buildDirManager
+                .setParametersAndRequestParse(BuildDirParameters(this),
+                                              BuildDirManager::REPARSE_DEFAULT);
+        }
+    });
 }
 
 void CMakeBuildConfiguration::initialize()