Update maintainers.txt for smart_ptr/make_shared

Added self (maintainer of make_shared and allocate_shared for arrays,
make_unique)

libs/maintainers.txt

@@ -98,6 +98,7 @@ serialization         Robert Ramey <ramey -at- rrsd.com>
 signals               Douglas Gregor <dgregor -at- cs.indiana.edu>
 signals2              Frank Mori Hess <fmhess -at- users.sourceforge.net>
 smart_ptr             Beman Dawes <bdawes -at- acm.org>, Peter Dimov <pdimov -at- pdimov.com>
+smart_ptr/make_shared Glen Fernandes <glenfe -at- live.com>
 spirit                Joel de Guzman <joel -at- boost-consulting.com>, Hartmut Kaiser <hartmut.kaiser -at- gmail.com>
 statechart            Andreas Huber <ahd6974-boostorg -at- yahoo.com>
 static_assert         John Maddock <john -at- johnmaddock.co.uk>