It is not necessary at all. So remove it.
This also breaks an inclusion cycle mem.h->avutil.h->common.h->mem.h.
Reviewed-by: Paul B Mahol <onemda@gmail.com>
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>