NEW DELHI - India’s army chief on Friday withdrew a lawsuit in which he had sought a change in his birth date that would have let him remain in his post an extra year, ending a showdown with the government. General V.K. Singh withdrew his appeal after the Supreme Court upheld the government’s stand that the army chief’s birthday in official records was May 10, 1950. Singh, who maintained he was born on the same day a year later and that a transcription mistake had been made in his records, would have been able to remain in office an additional 12 months had the court upheld his appeal.