Utils: Add a FilePath::lastModified() interface

And a local implementation.

Change-Id: I26400d960890c1cfb3daf82e6bfdeffa68455471
Reviewed-by: David Schulz <david.schulz@qt.io>

src/libs/utils/fileutils.cpp

@@ -1302,6 +1302,12 @@ uint FilePath::hash(uint seed) const
     return qHash(m_data, seed);
 }
 
+QDateTime FilePath::lastModified() const
+{
+    QTC_CHECK(!needsDevice());
+    return toFileInfo().lastModified();
+}
+
 QTextStream &operator<<(QTextStream &s, const FilePath &fn)
 {
     return s << fn.toString();

src/libs/utils/fileutils.h

@@ -171,6 +171,7 @@ public:
     bool isEmpty() const;
 
     uint hash(uint seed) const;
+    QDateTime lastModified() const;
 
     // NOTE: Most FilePath operations on FilePath created from URL currently
     // do not work. Among the working are .toVariant() and .toUrl().