LBJ ASKS MAHON FOR HIS VOTE ON POVERTY BILL, OFFERS TO CALL CHARLES GUY; GOVERNOR'S VETO AMENDMENT; OLIN TEAGUE'S VOTE; LBJ SAYS OTHERS WILL VOTE FOR BILL IF MAHON DOES, READS NYT STORY COMPARING VOTE ON BILL TO FDR'S DEFEAT ON SUPREME COURT-PACKING BILL