first usable version of kernel and commands

After an year of hard work, this is a first "usable" version of Jehanne.

qa/kern/syscall.c

@@ -0,0 +1,25 @@
+
+#include <u.h>
+#include <libc.h>
+
+void
+main(void)
+{
+	char buf[1024];
+	int i, n, oldn, fail;
+	int fd;
+
+	fail = 0;
+	for(i = 0; i < 10000; i++){
+		fd = open("/proc/1/status", OREAD);
+		n = read(fd, buf, sizeof buf);
+		if(i != 0 && n != oldn){
+			fprint(2, "read %d, want %d\n", n, oldn);
+			fail++;
+		}
+		oldn = n;
+		close(fd);
+	}
+	print("PASS\n");
+	exits("PASS");
+}