Log Message:
-----------
Improve comment about when to clean generated files.
Modified Files:
--------------
pgsql/src/interfaces/ecpg/preproc:
Makefile (r1.138 -> r1.139)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/preproc/Makefile?r1=1.138&r2=1.139)