declare base add_casted_stat overload as inline and unbreak build
declare base add_casted_stat overload as inline and unbreak build

gcc with our paranoid warning levels complains that add_casted_stat
function (not template) is not declared before being defined.

Which kind of makes sense as duplicating trivial 'proxy' function in
all compile units is not what we need. Inline fixes it.

Change-Id: I28cef250b68ef4b4c93c3ba271953b2bd5bcb83f
Reviewed-on: http://review.couchbase.org/13337
Tested-by: Dustin Sallings <1c08efb9b3965701be9d700d9a6f481f1ffec3ea@spy.net>
Reviewed-by: Dustin Sallings <1c08efb9b3965701be9d700d9a6f481f1ffec3ea@spy.net>

membase/ep-engine,hisundar/ep-engine,daverigby/kv_engine,owendCB/ep-engine,owendCB/ep-engine,jimwwalker/ep-engine,couchbaselabs/ep-engine,couchbaselabs/ep-engine,couchbase/ep-engine,jimwwalker/ep-engine,membase/ep-engine,owendCB/ep-engine,teligent-ru/ep-engine,daverigby/ep-engine,abhinavdangeti/ep-engine,daverigby/ep-engine,couchbaselabs/ep-engine,teligent-ru/ep-engine,abhinavdangeti/ep-engine,daverigby/ep-engine,couchbaselabs/ep-engine,sriganes/ep-engine,daverigby/kv_engine,membase/ep-engine,daverigby/kv_engine,couchbase/ep-engine,sriganes/ep-engine,abhinavdangeti/ep-engine,abhinavdangeti/ep-engine,membase/ep-engine,jimwwalker/ep-engine,couchbase/ep-engine,couchbaselabs/ep-engine,owendCB/ep-engine,hisundar/ep-engine,sriganes/ep-engine,daverigby/ep-engine,sriganes/ep-engine,jimwwalker/ep-engine,couchbase/ep-engine,abhinavdangeti/ep-engine,hisundar/ep-engine,hisundar/ep-engine,daverigby/kv_engine,teligent-ru/ep-engine,teligent-ru/ep-engine