[don't abort if DrIFT is not installed
John Meacham <john@repetae.net>**20090218080847
 Ignore-this: a1d3ecf56256f5d7164998f8d5a142f2
] hunk ./configure.ac 27
-    AC_MSG_ERROR([ DrIFT not found get it from http://repetae.net/computer/haskell/DrIFT/])
+    echo [DrIFT not found: using preprocessed files]