GenericProject: fix sorting file list when appending an entry

pos was -1 for a value that should have been appended as
last element to the list. Unfortunately, list->insert
treats -1 as prepending in front of the list, which lead
to incorrectly sorted lists.

The function got broken during the review process of
the introducing commit 758544c058.

Change-Id: I693e4d79b0d493deeac0ea8781d637fe50d008b8
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/genericprojectmanager/genericproject.cpp

@@ -239,6 +239,9 @@ bool GenericProject::saveRawList(const QStringList &rawList, const QString &file
 static void insertSorted(QStringList *list, const QString &value)
 {
     int pos = Utils::indexOf(*list, [value](const QString &s) { return s > value; });
+    if (pos == -1)
+        list->append(value);
+    else
         list->insert(pos, value);
 }