LIGHTS, CAMERA: Among the biggest fans of the Old County Courthouse are the producers of the television series “Gabriel’s Fire.” The series stars James Earl Jones, and it has filmed at the Santa Ana locale three times since it went on the air last year. . . . A county spokeswoman says the average movie or TV crew spends $4,000 to shoot at the courthouse, where an extensive renovation was completed in 1989. Prices vary by room, the most expensive being the original courtroom at $2,000 a day.