Investigate different ways of writing to stdout

I came across this video the other day: https://www.youtube.com/watch?v=nH1YT1mrPt0
It's a faster(but much less flexible) way of doing logging.

The most important thing that I got out of it was the fact that the C library will do buffering. The lowest level that we do is to use [`fputs`](https://github.com/apache/logging-log4cxx/blob/18dd6730085fd2158e64e5588da56f98852a6812/src/main/cpp/systemoutwriter.cpp#L78). This will go through the C library and use the builtin C library buffering.

Since we have the ability to buffer data in log4cxx already using a `BufferedWriter`, do a test to see if it would be faster to avoid the C library buffering and do a `write()` system call directly to write data out.

Start with src/main/cpp/systemoutwriter.cpp, especially the fputs call, and inspect the existing BufferedWriter path. Compare direct write() calls with the current C-library-buffered approach under equivalent logging conditions. Done means a reproducible test or benchmark reports whether bypassing C buffering is faster.

Written by the indexing model from the issue text.