[truetype] Optimize bytecode movements. Replacing FT_MulDiv with FT_MulFix gives large performance gains. * src/truetype/ttinterp.h (TT_ExecContextRec): Store "projected" freedom vector. * src/truetype/ttinterp.c (Compute_Funcs): Compute "projected" freedom vector. (Direct_Move, Direct_Move_Orig, Compute_Point_displacement): Use it.