The Fabulous Thunderbirds, Dr. John, Buddy Guy, B.B. King and Carlos Santana served up a seven-hour concert at Costa Mesa’s (Calif.) Pacific Amphitheater Sunday. The T-Birds, Dr. John and Guy were solid, but too brief. King provided the event’s major glitch, arriving late. But it was made up for in part when he later joined Santana, whose Latin-rock made him a curious headliner for this fun, flawed bluesfest.