core: Fix setting of the chain_model signature result.

* src/verify.c (parse_trust): Fix detection of "chain" keyword.
--

Fixes-commit: da6f3dc0c53f11f7432b3c258702db07d6c37f9a
from 2007 shortly after introducing this.  I doubt that this info has
ever been used (it is for qualified signatures, which are only
supported using the legacy German RegTP rules for them which were soon
overturned by the commercial CAs).

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

src/verify.c

@@ -663,7 +663,7 @@ parse_trust (gpgme_signature_t sig, gpgme_status_code_t code, char *args)
         {
           while (*args == ' ')
             args++;
-          if (!strncmp (args, "chain", 2) && (args[2] == ' ' || !args[2]))
+          if (!strncmp (args, "chain", 5) && (args[5] == ' ' || !args[5]))
             sig->chain_model = 1;
         }
     }