Include sys/types.h and sys/wait.h for waitpid

(cherry picked from commit 8b2c6d44cac206b61dffd965863336e6f803fc66)

Change-Id: Ice1f6d956c11aaefd3d846c12121f08613a94446
diff --git a/tests/sys_select_test.cpp b/tests/sys_select_test.cpp
index 5252e6b..c1732ee 100644
--- a/tests/sys_select_test.cpp
+++ b/tests/sys_select_test.cpp
@@ -20,6 +20,8 @@
 #include <signal.h>
 #include <stdlib.h>
 #include <sys/select.h>
+#include <sys/types.h>
+#include <sys/wait.h>
 
 TEST(sys_select, fd_set_smoke) {
   fd_set fds;