[truetype] Relocate the interpreter pointer. This reduces dereferencing when calling the interpreter. * include/freetype/internal/tttypes.h (TT_Face): Move it from here... * src/truetype/ttinterp.h (TT_ExecContext): ... to here. * src/truetype/ttobjs.c (tt_size_init_bytecode): Move its initialization * src/truetype/ttinterp.c (TT_New_Context): ... to here. (TT_Run_Context): Updated.