Add missing include files

Per compiler griping on OS X.

repmgr-action-daemon.c

@@ -18,6 +18,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <signal.h>
 #include <sys/stat.h>			/* for stat() */
 
 #include "repmgr.h"

repmgr-client.c

@@ -54,6 +54,7 @@
 
 #include <unistd.h>
 #include <sys/stat.h>
+#include <signal.h>
 
 #include "repmgr.h"
 #include "compat.h"