Changed Incrs() Stat calls to Incr().

Change-Id: I4ea025a0b2462b11a42c28304876e3cb4de2da4d
Reviewed-on: http://review.couchbase.org/38872
Reviewed-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Tested-by: Pratap Chakravarthy <prataprc@couchbase.com>