* load.c (load_lock): revert r38744. it should acquire new thread
  shield.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38749 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* load.c (load_lock): if thread shield is destroyed and there is no
  waiting thread, insert new thread shield into load_table.
  [Bug #7530] [ruby-core:50645]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38750 b2dd03c8-39d4-4d8f-98ff-823fe69b080e