cleanup(common): nit-pick cleanup to #9140 (#9149)
cleanup(common): nit-pick cleanup to #9140 (#9149)

* consistently use `#if defined(_MSC_VER)` over `#ifdef _MSC_VER`
* `s/_MSVC_VER)/_MSC_VER/`
googleapis/google-cloud-cpp,googleapis/google-cloud-cpp,googleapis/google-cloud-cpp,googleapis/google-cloud-cpp