Bump version to libpng-1.4.0beta60

CHANGES

diff --git a/CHANGES b/CHANGES
index dd0c6f4..f7fa299 100644
--- a/CHANGES
+++ b/CHANGES
@@ -2130,6 +2130,8 @@
   Added sections about the git repository and our coding style to the
     documentation
 
+version 1.4.0beta60 [May 16, 2009]
+
 version 1.4.0betaN [future]
   Build shared libraries with -lz and sometimes -lm.