1. Print broker address for debug.
2. Do not letting backup job cancelled if it already in state UPLOAD_INFO.
3. Cancel task on Backends when job is cancelled.
4. Show detail progress of backup and restore job.
5. Make 'show snapshot' result more readable.
6. Change upload and download thread num of backup and restore in Backend to 1.
* Reduce UT binary size
Almost every module depend on ExecEnv, and ExecEnv contains all
singleton, which make UT binary contains all object files.
This patch seperate ExecEnv's initial and destory to anthor file to
avoid other file's dependence. And status.cc include debug_util.h which
depend tuple.h tuple_row.h, and I move get_stack_trace() to
stack_util.cpp to reduce status.cc's dependence.
I add USE_RTTI=1 to build rocksdb to avoid linking librocksdb.a
Issue: #292
* Update
