Fixed missing initialization of Vtr::Level::VTag._incomplete.
Fixed missing initialization of Vtr::Level::VTag._incomplete.

jcowles/OpenSubdiv,takahito-tejima/OpenSubdiv,anshuarya/OpenSubdiv,xldeveloper/OpenSubdiv,shengfuintel/OpenSubdiv,anshuarya/OpenSubdiv,nyotis/OpenSubdiv,takahito-tejima/OpenSubdiv,c64kernal/OpenSubdiv,shengfuintel/OpenSubdiv,jcowles/OpenSubdiv,xldeveloper/OpenSubdiv,nyotis/OpenSubdiv,poljere/OpenSubdiv,takahito-tejima/OpenSubdiv,xldeveloper/OpenSubdiv,nyotis/OpenSubdiv,poljere/OpenSubdiv,c64kernal/OpenSubdiv,lookup1980/OpenSubdiv,c64kernal/OpenSubdiv,anshuarya/OpenSubdiv,lookup1980/OpenSubdiv,lookup1980/OpenSubdiv,jcowles/OpenSubdiv,shengfuintel/OpenSubdiv,poljere/OpenSubdiv