multi-employer worksite doctrine, general contractor liability for safety of employees of subcontractor, inspection of jobsite by competent person, serious, appeal, substantial evidence, entire record, statutory right, constitutional right, excess of statutory authority, improper procedure, error of law, substantial competent evidence, entire record as a whole, arbitrary or capricious, 29 CFR § 1926.20(b)(2), N.C.G.S. § 95-127(18), N.C.G.S. § 95-127(2), 29 U.S.C. § 654(a)(2)