Our coordinate system has the origo in the top left corner, PDF's one is
at the bottom left corner. So the page height affects the coordinate of
all widths and y positions. That page width is 870.25 in the case of the
bugdoc, but it was handled as 870 due to the integer rounding. The
coordinates and heights are now closer to the expected ones.

(cherry picked from commit a05dc747)

Change-Id: I9c7d77298df3850bbc170c9ace18120900d7e3fa
Reviewed-on: https://gerrit.libreoffice.org/38035Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>