Qt4BuildConfiguration: Fix extractSpecFromArguments with symlinked dirs

The canonical form of the -spec argument is a relative path if the
mkspec is a child of the mkspec dir. Since we resolve all symlinks for
the mkspec, we must do the same for the mkspec dir.

Task-number: QTCREATORBUG-7908
Change-Id: I24628c2d49ff7ad078caa6fd3896cb407d0d7906
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/plugins/qt4projectmanager/qt4buildconfiguration.cpp

@@ -485,6 +485,7 @@ Utils::FileName Qt4BuildConfiguration::extractSpecFromArguments(QString *args,
 
     Utils::FileName baseMkspecDir = Utils::FileName::fromUserInput(
             version->qmakeProperty("QT_HOST_DATA") + QLatin1String("/mkspecs"));
+    baseMkspecDir = Utils::FileName::fromString(baseMkspecDir.toFileInfo().canonicalFilePath());
 
     // if the path is relative it can be
     // relative to the working directory (as found in the Makefiles)