Depois de atualizar os pacotes (no Miktex), quase nada compila mais. Por exemplo:
\documentclass{article}
\usepackage{libertine}
\begin{document}
plop
\end{document}
resulta nos seguintes erros:
C:\Users\TL\AppData\Roaming\MiKTeX\2.9\tex\latex\libertine\libertine.sty:10: Undefined control sequence. [\ifxetex]
C:\Users\TL\AppData\Roaming\MiKTeX\2.9\tex\latex\libertine\libertine.sty:12: Extra \else. [\else]
C:\Users\TL\AppData\Roaming\MiKTeX\2.9\tex\latex\libertine\libertine.sty:12: Undefined control sequence. [\else\ifluatex]
C:\Users\TL\AppData\Roaming\MiKTeX\2.9\tex\latex\libertine\libertine.sty:14: Extra \else. [\else]
C:\Users\TL\AppData\Roaming\MiKTeX\2.9\tex\latex\libertine\libertine.sty:16: Extra \fi. [\fi]
C:\Users\TL\AppData\Roaming\MiKTeX\2.9\tex\latex\libertine\libertine.sty:16: Extra \fi. [\fi\fi]
C:\Users\TL\AppData\Roaming\MiKTeX\2.9\tex\latex\libertine\libertine.sty:289: Undefined control sequence. [ \defaultfontfeatures]
C:\Users\TL\AppData\Roaming\MiKTeX\2.9\tex\latex\libertine\libertine.sty:290: LaTeX Error: Missing \begin{document}. [ L]
C:\Users\TL\AppData\Roaming\MiKTeX\2.9\tex\latex\libertine\libertine.sty:296: Undefined control sequence. [ \setmainfont]
No entanto, o pacoteiftexestá instalado e não háifxetexpacote para download. Parece queifptexfornece \ifXeTeX, não ifxetex(sério!?!...). Problemas semelhantes surgem para \ifluatex.
Como consertar isto ?