load.c: defer initalization of static-linked-ext

* load.c (rb_feature_p): deal with default loadable suffixes.
* load.c (load_lock): initialize statically linked extensions.
* load.c (search_required, rb_require_safe): deal with statically
  linked extensions.
* load.c (ruby_init_ext): defer initalization of statically linked
  extensions until required actually.  [Bug #8883]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43514 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2013-11-03

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43515 b2dd03c8-39d4-4d8f-98ff-823fe69b080e