Fixup includes

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/libfio.c b/libfio.c
index 76a36a6..668df45 100644
--- a/libfio.c
+++ b/libfio.c
@@ -23,6 +23,8 @@
  */
 
 #include <string.h>
+#include <sys/types.h>
+#include <signal.h>
 #include "fio.h"
 
 /*