Include missing header files

Bug: https://bugs.gentoo.org/895060

diff --git a/pcl/pcl.c b/pcl/pcl.c
index 58d8605..313370e 100644
--- a/pcl/pcl.c
+++ b/pcl/pcl.c
@@ -22,6 +22,8 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
 #include "pcl_config.h"
 #include "pcl.h"
 #include "pcl_private.h"
-- 
2.41.0