revert changeset 500a5d97511a, re-enabling HOL-Proofs-Lambda

--- a/src/HOL/IsaMakefile	Mon Mar 26 20:07:41 2012 +0200
+++ b/src/HOL/IsaMakefile	Mon Mar 26 20:09:18 2012 +0200
@@ -65,6 +65,7 @@
   HOL-Predicate_Compile_Examples \
   HOL-Prolog \
   HOL-Proofs-ex \
+  HOL-Proofs-Lambda \
   HOL-SET_Protocol \
   HOL-SPARK-Examples \
   HOL-SPARK-Manual \
@@ -80,8 +81,6 @@
   HOL-ZF
     # ^ this is the sort position
 
-# FIXME  HOL-Proofs-Lambda
-
 generate: \
   HOL-HOL4-Generate \
   HOL-HOL_Light-Generate