Use the listings.sty option upquote=true

Fixes modelica#3122.

mlsshared.sty

@@ -19,6 +19,7 @@
 \usepackage{newtxtt}
 \fi
 
+\usepackage{textcomp}
 \usepackage{listings}
 \usepackage{color}
 \usepackage[table]{xcolor}
@@ -188,6 +189,7 @@
   mathescape=true,
   breaklines=true,                 % automatic line breaking only at white-space
   keepspaces,                      % don't remove space such as those after closing parenthesis
+  upquote=true,                    % Don't turn apostrophe/backtick into single quotation marks.
   captionpos=b,                    % sets the caption-position to bottom
   commentstyle=\color{commentcolor}\sffamily,
   keywordstyle=\color{red},        % Unused keyword style in bright red to make it easy to detect and fix.