Summary:
This patch factors out the logic that reads a (potentially compressed) blob
from a file into a separate helper method `GetRawBlobFromFile`, and cleans
up the code a bit. Also, errors during decompression are now logged/propagated
to the user by returning a `Status` code of `Corruption`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6093
Test Plan: `make check`
Differential Revision: D18716673
Pulled By: ltamasi
fbshipit-source-id: 44144bc064cab616862d5643f34384f2bae6eb78
d9314a9214