Fallback to regular halt/1 if halt/2 is undefined.
Fallback to regular halt/1 if halt/2 is undefined.

Which is the case in R14.

Change-Id: I205fa969d93ae1e313d05c23539214c95b9c103a
Reviewed-on: http://review.couchbase.org/39228
Tested-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>

mschoch/ns_server,mschoch/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,t3rm1n4l/ns_server,membase/ns_server,mschoch/ns_server,ceejatec/ns_server,nimishzynga/ns_server,membase/ns_server,ceejatec/ns_server,membase/ns_server,nimishzynga/ns_server,mschoch/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,ceejatec/ns_server,mschoch/ns_server,mschoch/ns_server,nimishzynga/ns_server,t3rm1n4l/ns_server,nimishzynga/ns_server,t3rm1n4l/ns_server,membase/ns_server,nimishzynga/ns_server,membase/ns_server,membase/ns_server,ceejatec/ns_server,nimishzynga/ns_server