Fix Coverity Scan warning on uninitialized variable
Fix Coverity Scan warning on uninitialized variable

*** CID 157851:  Uninitialized members  (UNINIT_CTOR)
/forestdb/src/hbtrie.h: 158 in HBTrieValue::HBTrieValue(unsigned char,
void *, unsigned long)()
152                 valueLen = _value_len;
CID 157851:  Uninitialized members  (UNINIT_CTOR)
Non-static class member "offset" is not initialized in this
constructor nor in any functions that it calls.

Change-Id: I09c75d500663437862d549c5d127aea7400b41cb
Reviewed-on: http://review.couchbase.org/70878
Reviewed-by: abhinav dangeti <d73ef2279de6577f7bf081737ee47554bbb7dc82@couchbase.com>
Tested-by: Sundararaman Sridharan <333a3f71d3ad6e01fc953c4fa06bc1f3cd014910@couchbase.com>

wurikiji/forestdb,wurikiji/forestdb,couchbase/forestdb,couchbase/forestdb