QbsProjectManager: Cache run environment

Setting up the qbs run environment is not free, and the respective code
gets triggered from other plugins much more often than expected.

Task-number: QTCREATORBUG-20175
Change-Id: I6529718d20738140963486caef103d6d17958d50
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/qbsprojectmanager/qbsproject.cpp

@@ -452,6 +452,7 @@ void QbsProject::updateAfterParse()
     updateCppCodeModel();
     updateQmlJsCodeModel();
     emit fileListChanged();
+    emit dataChanged();
 }
 
 void QbsProject::delayedUpdateAfterParse()
@@ -609,6 +610,7 @@ void QbsProject::updateAfterBuild()
         m_extraCompilersPending = false;
         updateCppCodeModel();
     }
+    emit dataChanged();
 }
 
 void QbsProject::registerQbsProjectParser(QbsProjectParser *p)