Introduce a new preprocessor symbol (R__COMPLETE_MEM_TERMINATION) that allows for
better tracking of memory leak.   When ROOT is compiled with this symbols is defined,
globally held objects will be deleted at the time of the process termination.

With this symbol defined, some tests (root.exe -b -l -q ; test/stress ;) run under
'valgrind --leak-check=yes' with no memory leak reports (but still a few still
reacheable blocks).   However, this does not yet support (i.e. segfault at termination) 
the case where TFunctions are created on the 'CINT' stack (and thus fails roottest) and
some uses of CINT functions for fitting ...  and probably also fails on Windows.


git-svn-id: http://root.cern.ch/svn/root/trunk@37531 27541ba8-7e3a-0410-8455-c3a389f83636