Project: Avoid copying the entire files(...) list

Avoid copying the entire list of files known to a project just to
filter out a couple of files from it.

Change-Id: I58b2e323f9678058ba482353eb777a55189fe05d
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/qmakeprojectmanager/qmakeproject.cpp

@@ -764,7 +764,11 @@ static void notifyChangedHelper(const FilePath &fileName, QmakeProFile *file)
 void QmakeProject::notifyChanged(const FilePath &name)
 {
     for (QmakeProject *project : s_projects) {
-        if (project->files(QmakeProject::SourceFiles).contains(name))
+        if (!project
+                 ->files([&name](const ProjectExplorer::Node *n) {
+                     return Project::SourceFiles(n) && n->filePath() == name;
+                 })
+                 .isEmpty())
             notifyChangedHelper(name, project->rootProFile());
     }
 }