Properly activate the pthread support on GNU/Hurd.

Originally submitted as a patch to the Debian Heimdal package:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=483281

Signed-Off-By: Jelmer Vernooij <jelmer@debian.org>

Signed-off-by: Love Hörnquist Åstrand <lha@h5l.org>

cf/pthreads.m4

@@ -39,6 +39,11 @@ case "$host" in
 	PTHREAD_CFLAGS=-pthread
 	PTHREAD_LIBADD=-pthread
 	;;
+*-*-gnu*)
+	native_pthread_support=yes
+	PTHREADS_CFLAGS=-pthread
+	PTHREAD_LIBADD="-pthread -lpthread"
+	;;
 *-*-linux* | *-*-linux-gnu)
 	case `uname -r` in
 	2.*|3.*)