unit test testTdf158743 in PNGExportTests.cxx fails for me

[Regina Henschel]

Hi all,

the unit test testTdf158743 fails for me.
https://opengrok.libreoffice.org/xref/core/sd/qa/unit/PNGExportTests.cxx?r=25276df1#304

I get Actual 855 instead of the mentioned expected 842 (tested as less 
than 850). I have build with --disable-skia because building Skia fails 
for me.

Might it be, that the result in the unit test depends on whether Skia is 
used or not?

Kind regards,
Regina