All server logs were printed to stdout, while all client logs were
printed to stderr.
Instead, use stderr for warnings and errors, stdout for the others:
- stdout: verbose, debug, info
- stderr: warn, error
One log macro was provided for each log level (LOGV(), LOGD(), LOGI(),
LOGW(), LOGE()).
Add a generic macro LOG(LEVEL, ...) accepting a log level as parameter,
so that it is possible to write logging wrappers.
PR #3005 <https://github.com/Genymobile/scrcpy/pull/3005>
