rb_fd_clr         315 include/ruby/intern.h void rb_fd_clr(int, rb_fdset_t *);
rb_fd_clr        3566 thread.c       #define FD_CLR(i, f)	rb_fd_clr((i), (f))
rb_fd_clr        3619 thread.c       #define FD_CLR(i, f)	rb_fd_clr((i), (f))