wkd: Fix client issue with leading or trailing spaces in user-ids.

* common/recsel.c (recsel_parse_expr): Add flag -t.
* common/stringhelp.c: Remove assert.h.
(strtokenize): Factor code out to do_strtokenize.
(strtokenize_nt): New.
(do_strtokenize): Add arg trim to support the strtokenize_nt.
* common/t-stringhelp.c (test_strtokenize_nt): New test cases.

* tools/wks-util.c (wks_list_key): Use strtokenize_nt and the recsel
flag -t.
--

This fixes a bug with user ids with leading spaces because:

wks-client lists all mail addresses from the key and matches them to the
requested mail address.

If there are several user-ids all with the same mail address
wks-client picks one of them and then extracts exactly that user id.
However, here it does not match by the mail address but by the full
user-id so that we can be sure that there will be only one user-id in
the final key.

The filter built expression unfortunately strips leading blanks but
requires a verbatim match.  Thus it won't find the user id again and
errors out.

The new -t flag and a non-trimming strtokenize solves the problem.

Signed-off-by: Werner Koch <wk@gnupg.org>

doc/gpg.texi

@@ -4072,6 +4072,9 @@ are:
   @var{VALUE} spans to the end of the expression.
   @item -c
   The string match in this part is done case-sensitive.
+  @item -t
+  Leading and trailing spaces are not removed from @var{VALUE}.
+  The optional single space after @var{op} is here required.
 @end table
 
 The filter options concatenate several specifications for a filter of