[boost] Some patches to remove obsolete MSVC version checks

Hi, I've created patches to remove or simplify some ifdefs for MSVC versions which are now obsolete. There are many more to do. http://www.steveire.com/msvc_obsolete_versions_patches This is a followup to this thread: http://thread.gmane.org/gmane.comp.lib.boost.devel/243094 (Removing old config macro and increasing compiler requirements., 2013-07-29) The patches are most easily applied locally and reviewed with a git-svn checkout and git am. I'll also apply to get SVN access so I can commit patches myself. Thanks, Steve.