Use pico_rand for DHCP xid, run cmake in load command

cmd/load/main.go

@@ -26,6 +26,14 @@ func main() {
 }
 
 func run(buildDir string) error {
+	fmt.Println("Configuring...")
+	cmake := exec.Command("cmake", "-B", buildDir)
+	cmake.Stdout = os.Stdout
+	cmake.Stderr = os.Stderr
+	if err := cmake.Run(); err != nil {
+		return fmt.Errorf("cmake failed: %w", err)
+	}
+
 	fmt.Println("Building...")
 	cmd := exec.Command("make", "-C", buildDir)
 	cmd.Stdout = os.Stdout