Makefile: Do _not_ delete dummy .ml files of .ml4 files even when not needed anymore.
Makefile: Do _not_ delete dummy .ml files of .ml4 files even when not needed anymore.

git-svn-id: a49b465eaba45b67e2e1e4e0b2c256a71f59fecb@10015 85f007b7-540e-0410-9357-904b9bb8a0f7

SamB/coq