init: clean up more headers

We don't need everyone including <sys/system_properties.h>

Test: boot bullhead
Change-Id: I73d507e4f273678eaf15947725741e1e3b966cc6
diff --git a/init/property_service.cpp b/init/property_service.cpp
index 9857223..2aa89ff 100644
--- a/init/property_service.cpp
+++ b/init/property_service.cpp
@@ -24,6 +24,7 @@
 #include <limits.h>
 #include <netinet/in.h>
 #include <stdarg.h>
+#include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>