rb_fd_init, rb_fd_term, rb_fd_zero, rb_fd_set, rb_fd_clr, rb_fd_isset,
rb_fd_select, rb_fd_ptr, rb_fd_max, HAVE_RB_FD_INIT): new type,
functions, and macros for Windows.
* win32/win32.c (extract_fd, rb_w32_select): use rb_fdset_t to expand
fd_array if needed. [ruby-core:19946]
* win32/win32.c (copy_fd): new funcion for rb_w32_select().
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@21487 b2dd03c8-39d4-4d8f-98ff-823fe69b080e