MB-28453: doc_pre_expiry peeking at xattrs before decompression
MB-28453: doc_pre_expiry peeking at xattrs before decompression

We have a call to get_body_offset which is dangerous and not needed.
Blob::Blob will handle it correctly.

Change-Id: Ife418968f237d87336c01b97c7a9353e7ae30a33
Reviewed-on: http://review.couchbase.org/90492
Reviewed-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@gmail.com>
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine