[build] Fix build on RHEL7.3 latest

header inclusion have changed

Signed-off-by: Fabio M. Di Nitto <fdinitto@redhat.com>

lib/sam.c

@@ -46,6 +46,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <errno.h>
+#include <poll.h>
 
 #include <corosync/corotypes.h>
 #include <qb/qbipcc.h>