Summary:
In the off chance you have a `Microsoft.PowerShell_profile.ps1` profile the `execute_process` will load one's profile during running `cmake`, which will cause garbage output to be written to the `build_version.cc` file. If you add in a `-noprofile` flag, or you suppress output in your pshell profile, this is mitigated.
Closes https://github.com/facebook/rocksdb/pull/2168

Differential Revision: D4927003

Pulled By: siying

fbshipit-source-id: 83861752d6cf2627dd864eedd2acaa8aa8a6232e