marshal.c: Numerics are not tainted

* include/ruby/ruby.h (OBJ_TAINTABLE, OBJ_TAINT, OBJ_INFECT),
  marshal.c (r_entry0): all Numerics never be tainted now.
  [ruby-core:57346] [Bug #8945]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44891 b2dd03c8-39d4-4d8f-98ff-823fe69b080e