gpg-interface: trim CR from ssh-keygen -Y find-principals

We need to trim \r from the output of 'ssh-keygen -Y find-principals' on
Windows, or we end up calling 'ssh-keygen -Y verify' with a bogus signer
identity. ssh-keygen.c:2841 contains a call to puts(3), which confirms this
hypothesis. Signature verification passes with the fix.

Signed-off-by: pedro martelletto <pedro@yubico.com>

Author: martelletto

gpg-interface.c

@@ -509,7 +509,7 @@ static int verify_ssh_signed_buffer(struct signature_check *sigc,
 			if (!*line)
 				break;
 
-			trust_size = strcspn(line, "\n");
+			trust_size = strcspn(line, "\r\n");
 			principal = xmemdupz(line, trust_size);
 
 			child_process_init(&ssh_keygen);