Summary:
On older macOS like 10.10 we saw the following compiler error:
```
/go/src/github.com/cockroachdb/cockroach/c-deps/rocksdb/env/env_posix.cc:845:19:
error: use of undeclared identifier 'CLOCK_THREAD_CPUTIME_ID'
clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts);
^
```
According to mac's `man clock_gettime`: "These functions first appeared in Mac
OSX 10.12". So we should not try to compile it on earlier versions.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5570
Test Plan:
verified it compiles now on 10.10. Also did some investigation to
ensure it does not cause regression on macOS 10.12+, although I do not
have access to such an environment to really test.
Differential Revision: D17322629
Pulled By: riversand963
fbshipit-source-id: e0a412223854f826b4d83e6d15c3739ff4620d7d
20dd828c01