FileUtils: Replace FileNameList with an alias

The functionality in that class is covered by initializers and
Utils::unique, so there is no need to keep a custom class.

This way FileNameList plays way nicer with utils/algorithm.h.

Change-Id: I8eeae6aca0558ecd998920c4fdfc5ea56bf75501
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>

src/libs/utils/fileutils.cpp

@@ -763,25 +763,6 @@ QTextStream &operator<<(QTextStream &s, const FileName &fn)
     return s << fn.toString();
 }
 
-int FileNameList::removeDuplicates()
-{
-    QSet<FileName> seen;
-    int removed = 0;
-
-    for (int i = 0; i < size(); ) {
-        const FileName &fn = at(i);
-        if (seen.contains(fn)) {
-            removeAt(i);
-            ++removed;
-        } else {
-            seen.insert(fn);
-            ++i;
-        }
-    }
-
-    return removed;
-}
-
 } // namespace Utils
 
 QT_BEGIN_NAMESPACE