Add more test for epoll in configure
I was trying to compile lttng-tools on centos 5 (yes I know too old), but configure did not complain.
We should test for the presence of these and fail configure or add a compat layer.
In file included from compat-epoll.c:33:
poll.h:72: error: 'EPOLLRDHUP' undeclared here (not in a function)
poll.h:74: error: 'EPOLL_CLOEXEC' undeclared here (not in a function)
compat-epoll.c: In function 'compat_epoll_create':
compat-epoll.c:84: warning: implicit declaration of function 'epoll_create1'