Summary:
This diff fixes the following compilation error in mac.
./third-party/rapidjson/reader.h:422:31: error: comparison of constant 256 with expression of type 'Ch' (aka 'char') is always true
[-Werror,-Wtautological-constant-out-of-range-compare]
if ((sizeof(Ch) == 1 || e < 256) && escape[(unsigned char)e])
~ ^ ~~~
1 error generated.
Test Plan: make db_test
Reviewers: haobo, sdong, igor, ljin
Reviewed By: ljin
Subscribers: leveldb
Differential Revision: https://reviews.facebook.net/D19245