How can I do the macro which will automatilcally choose font if compiles on Win (TNR font) or on Linux (Liberation for example). Using XeTex (TeXLive).
\documentclass[12pt]{article}
\usepackage{polyglossia}
\setdefaultlanguage[spelling=modern]{russian}
\setotherlanguage{english}
\setmainfont{Liberation Serif} %want to choose Liberation on Linux, TNR in Win
\newfontfamily\cyrillicfonttt[Script=Cyrillic, Scale=0.8]{Ubuntu-Light}