Added a check for poll.h.

diff --git a/server/process.c b/server/process.c
index 7eab25b..c89fa1c 100644
--- a/server/process.c
+++ b/server/process.c
@@ -33,6 +33,9 @@
 # include <sys/socket.h>
 #endif
 #include <unistd.h>
+#ifdef HAVE_POLL_H
+#include <poll.h>
+#endif
 
 #include "windef.h"
 #include "winbase.h"