runtime: fix freebsd build

notetsleep: nosplit stack overflow
        120	assumed on entry to notetsleep
        80	after notetsleep uses 40
        72	on entry to runtime.futexsleep
        16	after runtime.futexsleep uses 56
        8	on entry to runtime.printf
        -16	after runtime.printf uses 24

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/12047043

src/pkg/runtime/os_freebsd.c

@@ -61,7 +61,13 @@ runtime·futexsleep(uint32 *addr, uint32 val, int64 ns)
 		return;
 
 fail:
-	runtime·printf("umtx_wait addr=%p val=%d ret=%d\n", addr, val, ret);
+	runtime·prints("umtx_wait addr=");
+	runtime·printpointer(addr);
+	runtime·prints(" val=");
+	runtime·printint(val);
+	runtime·prints(" ret=");
+	runtime·printint(ret);
+	runtime·prints("\n");
 	*(int32*)0x1005 = 0x1005;
 }