load_wait, search_required, rb_require_safe), ext/extmk.rb: Fix
  a bug where a statically linked extension cannot be autoloaded.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8_6@11781 b2dd03c8-39d4-4d8f-98ff-823fe69b080e