Singer Rita Ora doesn’t seem too glum after her breakup with Kim Kardashian’s reality-TV star brother, Rob. The British blonde made a surprise performance at Bob and Harvey Weinstein’s holiday party in LA Wednesday for guests including Dustin Hoffman, “Silver Linings Playbook” star Chris Tucker, James Van Der Beek, DJ Paul Oakenfold and “How Do I Live” songwriter Diane Warren. “Rita was in the holiday spirit,” said a spy at the Smashbox Studios bash benefiting the Hurricane Sandy Relief Fund and Robin Hood Foundation. “She sang, then partied with friends at a table by the stage. She showed no signs of the holiday blues.” Harvey made a toast at the Samsung-sponsored fete but exited before Ora went on and nearly forgot his booty. “He was walking out with an entourage,” says a spy. “But several of the staff scurried back in to grab wrapped gifts for Harvey they forgot to give him.”