Automoc: fix #13572: issue with symbolic links

Now automoc always uses GetRealPath() so symbolic links are always
resolved and it doesn't end up with twice the same file, once with the real
path and once with the symlinked path in some setups where the source dir
can be accessed directly and via a symlink

Alex

Source/cmQtAutomoc.cxx

@@ -170,7 +170,8 @@ void cmQtAutomoc::SetupAutomocTarget(cmTarget* target)
       ++fileIt)
     {
     cmSourceFile* sf = *fileIt;
-    std::string absFile = sf->GetFullPath();
+    std::string absFile = cmsys::SystemTools::GetRealPath(
+                                                    sf->GetFullPath().c_str());
     bool skip = cmSystemTools::IsOn(sf->GetPropertyForUser("SKIP_AUTOMOC"));
     bool generated = cmSystemTools::IsOn(sf->GetPropertyForUser("GENERATED"));