There is no need to declare mpers printers in defs.h because
they are already declared in printers.h or native_printer_decls.h.
This complements commit
1e56814f77594a22a74ddee629639eb0bb7edf3a.
* defs.h (v4l2_ioctl): Remove.
extern int term_ioctl(struct tcb *, const unsigned int, long);
extern int ubi_ioctl(struct tcb *, const unsigned int, long);
extern int uffdio_ioctl(struct tcb *, const unsigned int, long);
-extern int v4l2_ioctl(struct tcb *, const unsigned int, long);
extern int tv_nz(const struct timeval *);
extern int tv_cmp(const struct timeval *, const struct timeval *);