um: Include sys/uio.h to have writev()

sys/uio.h gives us writev(), otherwise the build might fail on
some systems.

Fixes: 49da7e64f3 ("High Performance UML Vector Network Driver")
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Richard Weinberger 2018-10-30 12:58:11 +01:00
commit 0053102a86