* include/ruby/io.h (FMODE_WSPLIT): Removed.  The write() system call
  is not required to split.  It was useful to avoid whole process
  blocking in Ruby 1.8 but not useful since write() is invoked without
  GVL.
  (FMODE_WSPLIT_INITIALIZED): Ditto.

* io.c (wsplit_p): Removed.
  (io_writable_length): Removed.
  (rb_fcntl): Don't update the removed flags.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48476 b2dd03c8-39d4-4d8f-98ff-823fe69b080e