Welcome to the J.J. Starbuck guide at TV Tome. Dale Robertson, who seemed to have disappeared after Death Valley Days, shows up again with longhorns on his Cadillac as a billionaire businessman who just likes to help good folks, punish bad ones, and homilize in J. J. Starbuck (Tuesdays; 9 to 10 P.M.; NBC), one of several entries from the tireless Stephen J. Cannell. It's been a long time since Tales of Wells Fargo and Death Valley Days, so long that Dale Robertson's predecessor, a certain Mr. Reagan, as host of the latter traded his white hats for the White House. And yet, some things never change; in the 20 years since he left series television, time has stood still for Dale Robertson. His "new" character still wears 10-gallon white hats, Roy Rogers jackets and string ties, talks with a Texas accent so thick it would make J.R. gag, and drives a '64 Lincoln Continental with steer horns on the hood and a horn that honks The Eyes of Texas. Did anybody mention the word