* eval.c (stack_extend): streamlined rb_thread_restore_context()
	  to ensure O(1) time.  based on a patch by Brent Roman <brent AT
	  mbari.org>.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8_7@22544 b2dd03c8-39d4-4d8f-98ff-823fe69b080e