chroot: Add a little chroot program

This program changes the current filesystem root and spawns a shell.

Userland/chroot.cpp

@@ -0,0 +1,27 @@
+#include <stdio.h>
+#include <unistd.h>
+
+int main(int argc, char** argv)
+{
+    if (argc != 2) {
+        printf("usage: chroot <path>\n");
+        return 0;
+    }
+
+    if (chroot(argv[1]) < 0) {
+        perror("chroot");
+        return 1;
+    }
+
+    if (chdir("/") < 0) {
+        perror("chdir(/)");
+        return 1;
+    }
+
+    if (execl("/bin/Shell", "Shell", nullptr) < 0) {
+        perror("execl");
+        return 1;
+    }
+
+    return 0;
+}