Fix cross-build of security/libgcrypt.

Evidently this is an uncommittable monstrous kludge, but I can't
remember why now.

Index: security/libgcrypt/Makefile
===================================================================
RCS file: /cvsroot/pkgsrc/security/libgcrypt/Makefile,v
retrieving revision 1.56
diff -p -u -r1.56 Makefile
--- security/libgcrypt/Makefile	21 Apr 2013 14:44:53 -0000	1.56
+++ security/libgcrypt/Makefile	23 Apr 2013 13:29:21 -0000
@@ -37,6 +37,9 @@ CFLAGS+=		-fheinous-gnu-extensions
 
 .include "options.mk"
 
+# [TRC 20130328: XXX This is an uncommitable monstrous kludge.
+TOOL_DEPENDS+=	libgpg-error-[0-9]*:../../security/libgpg-error
+
 .include "../../security/libgpg-error/buildlink3.mk"
 .include "../../mk/pthread.buildlink3.mk"
 .include "../../mk/bsd.pkg.mk"