put core implementation of $$shadowed() into QMakeGlobals

to make it available to a wider audience

Change-Id: I7a706f8d31de97d8214ba5ea745e19d1dbfda1bc
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>

src/shared/proparser/qmakeglobals.cpp

@@ -248,6 +248,18 @@ void QMakeGlobals::setDirectories(const QString &input_dir, const QString &outpu
     }
 }
 
+QString QMakeGlobals::shadowedPath(const QString &fileName) const
+{
+    if (source_root.isEmpty())
+        return fileName;
+    if (fileName.startsWith(source_root)
+        && (fileName.length() == source_root.length()
+            || fileName.at(source_root.length()) == QLatin1Char('/'))) {
+        return build_root + fileName.mid(source_root.length());
+    }
+    return QString();
+}
+
 QString QMakeGlobals::getEnv(const QString &var) const
 {
 #ifdef PROEVALUATOR_SETENV