SAUDI ARABIA LONG LINGER THE KING IN RIYADH, THE DESERT CAPITAL OF SAUDI ARABIA, NERVOUS COURTIERS HAVE BECOME ACCUSTOMED TO KEEPING ONE EYE OUT FOR SIGNS OF REVOLT INSPIRED BY EGYPT'S GAMAL ABDEL NASSER, AND ONE EYE ON THE LATEST DISPATCHES FROM THE FRENCH RIVIERA . THERE, AILING KING SAUD, 61, IS INSTALLED IN NICE'S GLEAMING HOTEL NEGRESCO IN 55 ROOMS ON THE FIFTH FLOOR WITH HIS VEILED WIVES, CONCUBINES, A PASSEL OF OFFSPRING, COURTIERS AND MAIDS . LAST WEEK THE RUMORS WERE FLYING ALONG THE COTE D'AZUR THAT THE DYSPEPTIC SAUD WAS SICK UNTO DEATH . THERE SEEMED GOOD REASON FOR CONCERN, FOR SAUD IS SUPPOSED TO BE SUFFERING FROM HYPERTENSION, A WEAK HEART, A POLYP IN HIS DIGESTIVE TRACT, ASTHMA, AND ALLAH KNOWS WHAT ELSE . WHEN ELEVEN DOCTORS CONVERGED AT HIS BEDSIDE, THINGS LOOKED FROM THE OUTSIDE AT LEAST, PRETTY GRIM . IT TURNED OUT THAT SAUD WAS COMPLAINING ABOUT HIS LIVER (HIS OWN REMEDY : BANANA PUREE IN CHANTILLY CREAM WITH FIVE SCOOPS OF ICE CREAM FOR BREAKFAST), AND HIS BLOOD, FOR WHICH HIS DOCTORS QUICKLY ORDERED BOTTLES OF PLASMA AS A PRECAUTION . SAUD'S SPOKESMAN REASSURINGLY SQUELCHED THE FLURRY OF WORRY . DOCTORS ARE THERE, " HE SAID . " NOT BECAUSE THE KING IS VERY, VERY SICK BUT BECAUSE OF THE IMPORTANCE AND THE POWER OF THEIR PATIENT . " OR, AS RADIO MECCA PUT IT TO SAUD'S SUBJECTS : " THE KING IS IN GOOD HEALTH . /