MAJOR: polling: add event ports support (Solaris)

Event ports are kqueue/epoll polling class for Solaris. Code is based
on https://github.com/joyent/haproxy-1.8/tree/joyent/dev-v1.8.8.
Event ports are available only on SunOS systems derived from
Solaris 10 and later (including illumos systems).
diff --git a/doc/configuration.txt b/doc/configuration.txt
index 7543cc3..cc3e31f 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -616,6 +616,7 @@
    - maxzlibmem
    - noepoll
    - nokqueue
+   - noevports
    - nopoll
    - nosplice
    - nogetaddrinfo
@@ -1460,11 +1461,18 @@
   equivalent to the command-line argument "-dk". The next polling system
   used will generally be "poll". See also "nopoll".
 
+noevports
+  Disables the use of the event ports event polling system on SunOS systems
+  derived from Solaris 10 and later. It is equivalent to the command-line
+  argument "-dv". The next polling system used will generally be "poll". See
+  also "nopoll".
+
 nopoll
   Disables the use of the "poll" event polling system. It is equivalent to the
   command-line argument "-dp". The next polling system used will be "select".
   It should never be needed to disable "poll" since it's available on all
-  platforms supported by HAProxy. See also "nokqueue" and "noepoll".
+  platforms supported by HAProxy. See also "nokqueue", "noepoll" and
+  "noevports".
 
 nosplice
   Disables the use of kernel tcp splicing between sockets on Linux. It is