Update Windows build # and installer for 2.1c1.
diff --git a/PCbuild/BUILDno.txt b/PCbuild/BUILDno.txt
index 9aab842..04c63c3 100644
--- a/PCbuild/BUILDno.txt
+++ b/PCbuild/BUILDno.txt
@@ -33,6 +33,8 @@
 
 Windows Python BUILD numbers
 ----------------------------
+  13    2.1c1
+        12-Apr-2001
   12    2.1b2
         20-Mar-2001
   11    2.1b1