Added a check for poll.h.

diff --git a/server/request.c b/server/request.c
index d7602da..4f943d0 100644
--- a/server/request.c
+++ b/server/request.c
@@ -48,6 +48,9 @@
 #include <sys/un.h>
 #endif
 #include <unistd.h>
+#ifdef HAVE_POLL_H
+#include <poll.h>
+#endif
 
 #include "windef.h"
 #include "winbase.h"