don't make $$TEMPLATE_PREFIX available any more

this is a purely internal variable. projects are supposed to
query $$TEMPLATE only.

Change-Id: I32a3aa7012a4fedcf6e77e2e1302ed978baac700
Reviewed-by: Joerg Bornemann <joerg.bornemann@nokia.com>

qmake/project.cpp

@@ -1315,10 +1315,6 @@ QMakeProject::read(uchar cmd)
 {
   again:
     if ((cmd & ReadSetup) && base_vars.isEmpty()) {
-        // hack to get the Option stuff in there
-        if(!Option::user_template_prefix.isEmpty())
-            vars["TEMPLATE_PREFIX"] = QStringList(Option::user_template_prefix);
-
         QString superdir;
         QString project_root;
         QString project_build_root;