init: add 'enable <service>' to negate "service <service>... disabled"

enable <servicename>
   Turns a disabled service into an enabled one as if the service did not
   specify disabled in the rc file.
   It will also start the service if needed.

Bug: 14472973
Change-Id: Id0b49cc687a2bc74f6f92e066c617724cc94908d
Signed-off-by: JP Abgrall <jpa@google.com>
diff --git a/init/init.h b/init/init.h
index 736b75b..c241912 100644
--- a/init/init.h
+++ b/init/init.h
@@ -74,6 +74,7 @@
                                  so it can be restarted with its class */
 #define SVC_RC_DISABLED 0x80  /* Remember if the disabled flag was set in the rc script */
 #define SVC_RESTART     0x100 /* Use to safely restart (stop, wait, start) a service */
+#define SVC_DISABLED_START 0x200 /* a start was requested but it was disabled at the time */
 
 #define NR_SVC_SUPP_GIDS 12    /* twelve supplementary groups */