What is the madd rule for the ending wāw in «فَلْيَعْبُدُوا رَبَّ»?

Al-Fīl and Quraysh: Applied Iẓhār, Ikhfāʾ, Idghām, Madd and Waqf

• Madd al-līn after fatḥah
• Natural madd; the next word starts with rāʾ
• Separate madd; the next letter is hamzah
• Connected madd with hamzah in the same word