Found on FreeBSD which fails to build without these headers.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <sys/types.h>
+#include <sys/wait.h>
#include <unistd.h>
#include "../cash_nss.h"
#include <unistd.h>
#include "../cash_nss.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <sys/types.h>
+#include <sys/wait.h>
#include <unistd.h>
#include "../cash_nss.h"
#include <unistd.h>
#include "../cash_nss.h"