[9fans] /fd/n

[erik quanstrom <quanstro@quanstro.net>]

it seems a number of p9p programs assume /fd/n is valid:

; rcsdiff toico.c
===================================================================
RCS file: RCS/toico.c,v
retrieving revision 1.1
diff -r1.1 toico.c
80c80
< 		readicon("/fd/0");
---
> 		readicon("/dev/fd/0");
; grep /fd/ ../*.c ../*/*.c | grep -v /dev/
../strings.c:		stringit("/fd/0");
../acme/acme.c:	sprint(buf, "/fd/%d", pfd[1]);
../page/filter.c:		sprint(fdbuf, "/fd/%d", fd);
../page/gs.c:	fprint(fd, "(/fd/3) (w) file dup (THIS IS NOT AN INFERNO BITMAP\\n) writestring flushfile\n");
../page/gs.c:	args[nargs++] = "-sOutputFile=/fd/3";
../page/gs.c:	gscmd(g, "/PAGEOUT (/fd/4) (w) file def\n");
../page/pdf.c:		sprint(fdbuf, "/fd/%d", fd);
../page/ps.c:		sprint(fdbuf, "/fd/%d", fd);
../page/ps.c:		fprint(ps->gs.gsfd, "(/fd/3) (w) file dup (THIS IS NOT A PLAN9 BITMAP 01234567890123456789012345678901234567890123456789\\n) writestring flushfile\n");