fix translation

Author: Vladimir Kotal

threads.tex

@@ -1313,7 +1313,7 @@
 converted into the one that is by inserting a locked section.
 \item this is obviously not very efficient
 \end{itemize}
-\item \emph{reentrantní} typically means that the function was designed
+\item \emph{reentrant} typically means that the function was designed
 with threads in mind
 \begin{itemize}
 \item \dots{}i.e. it works efficiently in multithreaded environment