WASHINGTON (Reuters) - U.S. private employers stepped up hiring in June and the number of Americans filing new claims for jobless benefits last week fell by the most in two months, hopeful signs for the struggling labor market. Employers outside government added 176,000 new workers to their payrolls last month, the ADP National Employment Report showed on Thursday, after increasing 136,000 in May. The government will release its closely watched employment report for June on Friday. While ADP has a poor track record of predicting nonfarm payrolls, it was a welcome sign for the labor market. ...