tests: Put a workaround for semihosted environment.

* tests/openpgp/defs.scm [*win32*]: Use --build-prefix option.

--

On the semihosted environment, output of simple gpgconf
--list-components includes drive name (like Z:), which results failure
of command invocation.  This is a workaround.

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>

tests/openpgp/defs.scm

@@ -146,6 +146,9 @@
   (gpg-conf' "" args))
 (define (gpg-conf' input args)
   (let ((s (call-popen `(,(tool-hardcoded 'gpgconf)
+			 ,@(if *win32*
+			       (list '--build-prefix (getenv "objdir"))
+			       '())
 			 ,@args) input)))
     (map (lambda (line) (map percent-decode (string-split line #\:)))
 	 (string-split-newlines s))))