Fix misc-macro-parentheses warnings in system/core.

Add parentheses around macro arguments used beside operators.
Bug: 28705665

Change-Id: I9226f319e283be640eddc31687f75b51a8ef0ac6
diff --git a/init/util.h b/init/util.h
index c2efb01..b9496a9 100644
--- a/init/util.h
+++ b/init/util.h
@@ -23,7 +23,7 @@
 #include <string>
 #include <functional>
 
-#define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
+#define ARRAY_SIZE(x) (sizeof(x)/sizeof((x)[0]))
 
 #define COLDBOOT_DONE "/dev/.coldboot_done"