Change the definition of the functions in scm_ptobfuns so that

Change the definition of the functions in scm_ptobfuns so that
they get passed the port object, not the port's stream.
* ports.h (scm_ptobfuns): Rename all `stream' arguments to `port'.
* gc.c (scm_gc_sweep): Pass the port itself to the free function.
* genio.c (scm_putc, scm_puts, scm_lfwrite, scm_fflush, scm_getc):
Pass the port itself to the scm_ptobs function.
* ports.c (scm_close_port, scm_force_output, scm_flush_all_ports,
scm_generic_fgets): Same.
(putc_void_port, puts_void_port, write_void_port, flush_void_port,
getc_void_port, fgets_void_port, close_void_port): Just change the
argument names; these functions don't really do anything.
* fports.c (local_fgetc, local_fgets, local_fclose, local_fflush,
local_fputc, local_fputs, local_ffwrite, local_pclose): Take the
port as an argument, and use SCM_STREAM to get the stdio FILE *.
Also, use prototyped definitions, and get rid of the extra
declarations.
(scm_fptob, scm_pipob): We don't need casts here any more.
* strports.c (prinstpt): Use prototype declarations.
(stputc, stwrite, stputs, stgetc): Take the port as an argument,
and use SCM_STREAM to get the string info.  Also, use prototyped
definitions, and get rid of the extra declarations.
* vports.c (sfputc, sfwrite, sfputs, sfflush, sfgetc, sfclose,
noop0): Same.