merge from trunk (r28423)
* include/ruby/ruby.h (static inline rb_gc_guarded_ptr): prevent RB_GC_GUARD_PTR being removed by optimization.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_2@28467 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge from trunk (r28423)
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_2@28467 b2dd03c8-39d4-4d8f-98ff-823fe69b080e