Let's see if tcl/tk test runs on windows buildbot with this fix.
diff --git a/PCbuild/rt.bat b/PCbuild/rt.bat
index 91b39f7..f3c4829 100644
--- a/PCbuild/rt.bat
+++ b/PCbuild/rt.bat
@@ -30,7 +30,7 @@
 set suffix=
 set qmode=
 set dashO=
-set tcltk=
+set tcltk=tcltk
 
 :CheckOpts
 if "%1"=="-O" (set dashO=-O)     & shift & goto CheckOpts