init: Add noexec mount option

Change-Id: Ic13d66797a86d38432e79af0c3387ce986d0a19f
diff --git a/init/builtins.c b/init/builtins.c
index 9aa2345..ad52b19 100644
--- a/init/builtins.c
+++ b/init/builtins.c
@@ -273,6 +273,7 @@
     unsigned flag;
 } mount_flags[] = {
     { "noatime",    MS_NOATIME },
+    { "noexec",     MS_NOEXEC },
     { "nosuid",     MS_NOSUID },
     { "nodev",      MS_NODEV },
     { "nodiratime", MS_NODIRATIME },