* ioext.h: fix up prototypes.

* ioext.h: fix up prototypes.
* ioext.c (scm_dup_to_fdes): renamed from scm_primitive_dup2.
Scheme name is now dup->fdes.
(scm_dup_to_fdes): make the second argument optional and
fold in the functionality of scm_primitive_dup.
(scm_primitive_dup): deleted.
* fports.h (SCM_P): prototypes for scm_setvbuf, scm_setfileno.
* fports.c (scm_setbuf0): don't disable the setbuf if MSDOS or
ultrix are defined.  Use setvbuf instead of setbuf.
(scm_setvbuf): new procedure.
(scm_init_fports): intern _IOFBF, _IOLBF, _IONBF.
(scm_setfileno): moved from ioext.c.
(scm_fgets): cast SCM_STREAM to (FILE *), remove unused lp variable.
(top of file): Delete 25 lines of probably obsolete CPP hair for MSDOS.

* boot-9.scm (move->fdes, dup->port): use dup->fdes, not primitive-dup.
(dup->fdes): deleted, now done in C.