Summary:
Adapted a stderr logger from the option tests. Moved it to a separate
header so we can reuse it, e.g., from ldb subcommands for faster debugging. This
is especially useful to make errors/warnings more visible when running
"ldb repair", which involves potential data loss.
Test Plan:
ran options_test and "ldb repair"
$ ./ldb repair --db=./tmp/
[WARN] **** Repaired rocksdb ./tmp/; recovered 1 files; 588bytes. Some data may have been lost. ****
OK
Reviewers: IslamAbdelRahman, yhchiang, sdong
Reviewed By: sdong
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D56151
Siying Dong