Add a ucontext test from Nathan's testsuite.

regress/sys/kern/Makefile

@@ -1,6 +1,6 @@
-#	$NetBSD: Makefile,v 1.20 2002/11/30 09:31:31 jdolecek Exp $
+#	$NetBSD: Makefile,v 1.21 2003/01/30 19:47:00 thorpej Exp $
 
 SUBDIR+= execve extent getcwd ipf kqueue lock lockf pipe poll ras \
-	sigtramp sysvmsg sysvsem sysvshm unfdpass writev
+	sigtramp sysvmsg sysvsem sysvshm ucontext unfdpass writev
 
 .include <bsd.subdir.mk>

regress/sys/kern/ucontext/Makefile

@@ -0,0 +1,13 @@
+#	$NetBSD: Makefile,v 1.1 2003/01/30 19:47:00 thorpej Exp $
+
+WARNS=1
+
+PROG=   context
+SRCS=   context.c
+
+NOMAN=
+
+regress:
+	./context
+
+.include <bsd.prog.mk>

regress/sys/kern/ucontext/context.c

@@ -0,0 +1,36 @@
+/*	$NetBSD: context.c,v 1.1 2003/01/30 19:47:00 thorpej Exp $	*/
+
+#include <assert.h>
+#include <stdio.h>
+#include <ucontext.h>
+
+int
+main(int argc, char *argv[])
+{
+	ucontext_t u, v, w;
+	volatile int x, y;
+
+	x = 0;
+	y = 0;
+
+	printf("Start\n");
+
+	getcontext(&u);
+	y++;
+
+	printf(" X is %d\n", x);
+
+	getcontext(&v);
+
+	if ( x < 20 ) {
+		x++;
+		getcontext(&w);
+		printf("Adding one and going around.\n");
+		setcontext(&u);
+	}
+
+	printf("End, y = %d\n", y);
+	assert(y == 21);
+
+	return 0;
+}