Add missing <stdlib.h> for calloc()/free()/strtoul().

Change-Id: I22bf6e72b065142cfea5da8aff699043e8a8196b
diff --git a/libpackagelistparser/packagelistparser.cpp b/libpackagelistparser/packagelistparser.cpp
index 638cc43..5517b68 100644
--- a/libpackagelistparser/packagelistparser.cpp
+++ b/libpackagelistparser/packagelistparser.cpp
@@ -21,6 +21,7 @@
 #include <errno.h>
 #include <inttypes.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <sys/limits.h>