Make BrotliLibraryLoader.loadBrotli() call idempotent

[YSakhno]

Is it possible to make BrotliLibraryLoader.loadBrotli() method not load the native library if the library is already loaded? Currently I have to employ ClassLoader hack to list all loaded native libraries and see if brotli is already in there.

Note, that I cannot employ a flag of some kind (setting it to true or something after the first call to the aforementioned method), because my code is running as a plugin, and it is possible that some other plugin (written by someone else) already loaded native library for jbrotli.