minor change to smtpd.y (and yesterday)

[forsyth@plan9.cs.york.ac.uk forsyth@plan9.cs.york.ac.uk]

yesterday i couldn't receive mail from 3mail.3com.com, since
smtpd rejected the `mail from:' as having a syntax error.
the grammar in /sys/src/cmd/upas/smtp/smtpd.y is taken directly from
RFC 821, but (it turns out) RFC 1123 section 2.1 makes a blanket change
to all applications regarding host name formats, thus requiring a change to
the rfc821 grammar (but without specifying the change).

here are some diffs; the line numbers might not agree -- i haven't
got the CDROM online at the moment.

cpu% diff `{yesterday -940501 smtpd.y} .
90,92c90,91
< name		: a			={ $$ = cat(&$1, 0, 0, 0, 0 ,0, 0); }
< 		| a ld-str		={ $$ = cat(&$1, &$2, 0, 0, 0 ,0, 0); }
< 		| a ldh-str ld-str	={ $$ = cat(&$1, &$2, &$3, 0, 0 ,0, 0); }
---
> name		: ld-str		={ $$ = cat(&$1, 0, 0, 0, 0 ,0, 0); }
> 		| let-dig ldh-str ld-str ={ $$ = cat(&$1, &$2, &$3, 0, 0 ,0, 0); }

when first doing that diff, i discovered that several of the diagnostics
in /rc/bin/yesterday are not sent to the standard error; here are the diffs for that:

term% diff `{yesterday /rc/bin/yesterday} .
76c76
< 		'is not a backup day'
---
> 		'is not a backup day' >[1=2]
82c82
< 	echo 'yesterday: can''t find directory'
---
> 	echo 'yesterday: can''t find directory' >[1=2]