AIX does not know about MSG_DONTWAIT. Fortunately, nearly all sockets
are already set to O_NONBLOCK, so it's not even required to change the
code. It was only necessary to add this fcntl to the log socket which
lacked it. The MSG_DONTWAIT value has been defined to zero when unset
in order to make the code cleaner and more portable.
Also, on AIX, "hz" is defined, which causes a problem with one function
parameter in time.c. It's enough to rename the parameter there. Last,
fix a missing #include <string.h> in proxy.c.
SO_REUSEPORT does not exist on Linux but the checks are available in
the code. With a little patch, it's possible to implement the feature,
but the value of SO_REUSEPORT will still have to be known from userland.
This patch adds a workaround to this problem by figuring out the value
for the one used by SO_REUSEADDR.
