libknet/tests: Correct include path for poll.h
Fixes
/usr/include/sys/poll.h:1:2: error: redirec
ting incorrect #include <sys/poll.h> to <poll.h> [-Werror,-W#warnings]
| #warning redirecting incorrect #include <sys/poll.h> to <poll.h> |
Signed-off-by: Khem Raj <raj.khem@gmail.com>