Prot# GS-US-334-0154: A Phase 2b, Open-Label Study of 200 mg or 400 mg Sofosbuvir+RBV for 24 Weeks in Genotype 1 or 3 and Ledipasvir/Sofosbuvir (LDV/SOF) Fixed-Dose Combination (FDC) Tablet for 12 weeks in Genotype 1 or 4 HCV-Infected Subjects with Renal