Chris Brown’s “Under the Influence” has reached No. 1 on Billboard’s R&B/Hip-Hop Airplay chart, earning the singer his 10th No. 1 on the tally. Brown becomes only the fifth artist to reach 10 No. 1s on the R&B/Hip-Hop Airplay chart. “Under the Influence” is the third track on the extended edition of his ninth studio…