Add 'notify:pid' style readiness notifaction and 'readiness none'

This change expands the readiness notification system in Finit with the
native 'pid' style, which will remain the default readiness in Finit 4.x

For systems that want to transition to Finit 5.x early, a global option
to set 'readiness none' in /etc/finit.conf, has been added.  This change
the service default notification mode to 'notify:none', which can also
be set by Finit 4.x ('readiness pid') for select services.

Fixes #386.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/finit.c

@@ -69,6 +69,7 @@ int   single    = 0;		/* single user mode from kernel cmdline */
 int   bootstrap = 1;		/* set while bootrapping (for TTYs) */
 int   kerndebug = 0;		/* set if /proc/sys/kernel/printk > 7 */
 int   syncsec   = 0;		/* reboot delay */
+int   readiness = SVC_NOTIFY_PID;
 char *finit_conf= NULL;
 char *finit_rcsd= NULL;
 char *fstab     = NULL;