Log Message:
Update tex-geometry to 5.6.

Changes:
  * Package 'ifxetex' is loaded for robuster detection of XeTeX.
  * Fixed a bug where 'pass' option was not reset in \newgeometry.
  * Fixed a bug where paper width and height were swapped unnecessarily
    inside \newgeometry{} if 'landscape' is given as a class option.
  * Changed crop marks with elbow-shaped lines 17mm long and offset by 3mm.
  * Added 'showframe' and 'showcrop' as options shown in verbose mode.
  * Fixed typos and wrong figures, and revised expressions in the document.
  * Added missed things that had been fixed for v5.4 into changes.txt.
  * New paper size presets for ISO C-series: 'c0paper' to 'c6paper'.
  * Fixed a bug where overloading shipout in 'showframe' and/or 'showcrop'
    mode caused warnings when 'pdfpages' package is used.
  * Changed the shipout overloading process to use 'atbegshi' package.
    Options 'showframe' and 'showcrop' require the package.
  * Fixed a bug where restoring layoutwidth and layoutheight failed
    when \restoregeometry is called.
  * Fixed a bug that forced papersize to set the same length
    as the specified layoutsize.
  * Fixed a bug where page frame shown in 'showframe' mode was placed
    slightly wrong.
  * Fixed wrong 'h-part' calculation in verbose when bindingoffset
    or mag is specified.
  * Changed format and fixed values shown in verbose mode.