Printing heap on every processed sentence.

git-svn-id: https://scm.gforge.inria.fr/svn/coq/trunk@16949 85f007b7-540e-0410-9357-904b9bb8a0f7
Profile only when CAMLRUNPARAM is set.

git-svn-id: https://scm.gforge.inria.fr/svn/coq/trunk@16950 85f007b7-540e-0410-9357-904b9bb8a0f7
Better interface for allocation profiling.
Exporting print_heap in Vernac.
Adding a tactic to dump major heap.