1. rocksdb upgrade to 6.3.6
2. optimize the build scripts
3. fix build errors
4. add env variable for blobstore unit test
5. update git ignore file to ignore build and test result
6. modify open files limit for unit test
Signed-off-by: yuxiaobo <yuxiaobo@oppo.com>
Signed-off-by: slasher <shenjie1@oppo.com>
Signed-off-by: Victor1319 <834863182@qq.com>