fix FarPatchTables class nesting for LLVM-based compilers (Clang / ICC).
fix FarPatchTables class nesting for LLVM-based compilers (Clang / ICC).

fixes #172

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