kv/RocksDBStore: abort if rocksdb EIO, don't return incorrect result

kv/RocksDBStore: abort if rocksdb EIO, don't return incorrect result

If the underlying disk is missing, the current logic won't check the actual
reason why Get/Set failed, it will result to client get a empty key/value
pair which is not expected. The correct logic should be abort
right now. Otherwise, it will leads to undefined behavior.

Signed-off-by: Haomai Wang <haomai@xsky.com>
(cherry picked from commit 8c60b55d7d49bc6fa1d8d076c025fc83283c0776)

Conflicts:
	src/kv/RocksDBStore.cc (trivial)