fixed "double rev" bug that arose in situations where a % comment arose on the last line of a file without \n at the end

--- a/src/HOL/Tools/ATP/atp_util.ML	Sat Aug 11 11:31:05 2012 +0200
+++ b/src/HOL/Tools/ATP/atp_util.ML	Sat Aug 11 15:54:18 2012 +0200
@@ -82,7 +82,7 @@
       | strip_c_style_comment (#"*" :: #"/" :: cs) accum =
         strip_spaces_in_list true cs accum
       | strip_c_style_comment (_ :: cs) accum = strip_c_style_comment cs accum
-    and strip_spaces_in_list _ [] accum = rev accum
+    and strip_spaces_in_list _ [] accum = accum
       | strip_spaces_in_list true (#"%" :: cs) accum =
         strip_spaces_in_list true (cs |> chop_while (not_equal #"\n") |> snd)
                              accum